Background: Outdoor air pollution is considered a human carcinogen by the International Agency for Research on Cancer, particularly for its influence on lung cancer incidence and prognosis. While air pollution has not been consistently associated with breast cancer incidence, only one study has examined the impacts of air pollution on survival from breast cancer and was unable to consider important predictors of breast cancer mortality. We assessed whether PM exposures (PM2.5, PM2.510, and PM10) were associated with breast cancer specific-death and all-cause mortality.
Methods: The Nurses’ Health Studies (NHS and NHSII) are ongoing nationwide cohorts with detailed longitudinal data on medical history, addresses, lifestyle factors, and causes of death. We included women with confirmed Stage I-III breast cancer and collected additional clinical information from medical records. PM was estimated using GIS-based spatio-temporal models linked to addresses between 1989-2007. We performed Cox proportional hazards models to assess associations of breast cancer specific-death and overall mortality with PM exposures starting at diagnosis and updated over follow-up through June 2014.
Results: There were 1,211 breast-cancer specific deaths among 8,936 women with Stage I-III breast cancer. Overall, increases in PM were not associated with breast cancer survival (PM2.5: HR=1.09 95% CI 0.87, 1.36; PM2.5-10: HR=1.03 95% CI 0.85, 1.24; PM10: HR=1.05, 95% CI 0.89, 1.24, each per 10 μg/m3). However, each 10 μg/m3 increase in PM2.5 was associated with breast cancer death among participants with Stage I disease after adjusting for clinical, demographics and pre-diagnostic lifestyle factors (HR=1.69 95%CI 1.16, 2.47) and after additionally adjusting for post-diagnostic lifestyle factors (HR=1.64 95% CI 1.11, 2.43). Furthermore, PM exposures were associated with a 9-12% increase in all-cause mortality.
Overall, PM exposures were not associated with breast cancer survival; however, increases in PM2.5 did appear to adversely impact prognosis among Stage I breast cancer patients.
This work was funded by the NIH T32 CA 09001 and by a grant from the Susan G. Komen for the Cure ® (IIR13264020). We thank the NHS and NHSII participants and coordinators.
Citation Format: Natalie DuPre, Elizabeth M. Poole, Michelle D. Holmes, Jaime E. Hart, Peter James, Andrew Beck, Peter Kraft, Francine Laden, Rulla Tamimi. Particulate matter and traffic-related exposures in relation to breast cancer survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3278. doi:10.1158/1538-7445.AM2017-3278