Common Breast Cancer Susceptibility Variants in LSP1 and RAD51L1 Are Associated with Mammographic Density Measures that Predict Breast Cancer Risk

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38Environmental Epidemiology and 39Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland; 40Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden; 41Human Genetics, Genome Institute of Singapore, Singapore; 42Australian Mammographic Density Twins and Sisters Study (AMDTSS); 43Bavarian Breast Cancer Cases and Controls (BBCC); 44Determinants of Mammographic Density in Spain (DDM-Spain); 45EPIC-NL (Dutch part of European Prospective Investigation into Cancer Nutrition; EPIC-NL); 46European Prospective Investigation into Cancer–Norfolk I and II (EPIC-Norfolk I and II); 47Women's Learning the Influence of Family and Environment Study (LIFE); 48Magnetic Resonance Imaging in Breast Screening (MARIBS); 49Mayo Clinic Breast Cancer Study (MCBCS); 50Melbourne Collaborative Cohort Study (MCCS); 51Multiethnic Cohort Study (MEC); 52Mammography, Oestrogens and Growth Factors Study (MOG); 53Norwegian Breast Cancer Study (NBCS); 54Nurses' Health Study (NHS); 55Ontario Familial Breast Cancer Registry (OFBCR); 56Polish Breast Cancer Study (PBCS); 57Polish Nurses and Midwives Study (PNS); 58Singapore and Sweden Breast Cancer Study (SASBAC); and 59Sisters in Breast Cancer Screening (SIBS)

Authors' Affiliations: 1School of Population Health, Centre for Molecular Environmental, Genetic and Analytic Epidemiology, 2Department of Pathology, University of Melbourne; 3Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia; 4Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles; 5Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California; 6University Breast Center Franconia, Department of Gynecology and Obstetrics, University Hospital Erlangen Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-Nuremberg, Erlangen, Germany; 7Area de Epidemiologia Ambiental y Cáncer, Centro Nacional de Epidemiologia, Instituto de Salud Carlos III; 8Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Pública CIBERESP); 9Human Genetics Group, Spanish National Cancer Research Centre (CNIO); 10Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; 11Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; 12Department of Public Health and Primary Care, 13MRC Centre for Nutritional Epidemiology in Cancer Prevention and Survival (CNC), 14Department of Radiology, University of Cambridge, Addenbrooke's NHS Foundation Trust; 15MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom; 16Cancer Registry of Norway; 17Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo; 18Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway; 19CR-UK and EPSRC Cancer Imaging Centre; 20Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London; 21Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine; 22Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom; Departments of 23Health Sciences Research and 24Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; 25University of Hawaii Cancer Center, Honolulu, Hawaii; 26Section of Environment and Radiation, International Agency for Research on Cancer, Lyon, France; 27Institute of Community Medicine, Faculty of Health Sciences, University of Tromso, Tromso, Norway; 28Channing Laboratory, Brigham and Women's Hospital; 29Program in Molecular and Genetic Epidemiology; 30Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; 31Fred A. Litwin Center for Cancer Genetics, Samuel Lunenfeld Research Institute, 32Prosserman Centre for Health Research, Samuel Lunenfeld Research Institute, Mount Sinai Hospital; 33Department of Molecular Genetics, 34Dalla Lana School of Public Health, University of Toronto; 35Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Ontario, Canada; 36Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland; 37Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland; Departments of 38En