BACKGROUND: During the next several decades, 40 million American women born between 1946 through 1964 will face very high absolute risks of post-menopausal breast cancer, and 56 million women currently in their 20s and 30s will face substantial risks of pre-menopausal breast cancer. No study to date has predicted the future annual incidence rate and burden (number) of new cases in the United States (US) of both invasive and in-situ female breast cancers stratified by the estrogen receptor (ER) status of the tumor. However, such forecasts could help the oncology community develop a proactive roadmap to optimize prevention and treatment strategies.

METHODS: We constructed forecasts for women ages 30 through 84 in 2011 through 2030 using cancer incidence data from the Surveillance Epidemiology and End Results Program, novel age-period-cohort (APC) forecasting models, and population projections from the US Census Bureau. We modelled 16 subsets of breast tumors defined by positive versus negative ER status (a correlate of tumor biology and standard clinical predictive marker), invasive versus in-situ behavior, and four age group (two pre-menopausal groups 30 - 39 and 40 - 49, and two post-menopausal groups 50 - 69 and 70 - 84). Screening mammography is recommended for women ages 50 - 74 by the US Preventive Services Task Force and starting at age 40 by the American Cancer Society; the age-group-specific models allowed the APC model parameters to implicitly reflect screening effects in the population. For each subset we applied a second-generation APC forecasting model incorporating JoinPoint regression of breast cancer birth cohort effects.

RESULTS: The incidence of both invasive and in-situ ER+ tumors is expected to increase significantly during our forecast period. In contrast, the incidence of both invasive and in-situ ER- tumors is expected to decrease significantly. The total number of new tumors (invasive plus in-situ) is expected to rise more than 50% from 283,000 in 2011 to 441,000 in 2030 (plausible range from 353,000 to 466,700 cases). The proportion of new cases ages 70 - 84 is expected to increase from 24% to 35%, while the proportion ages 50 - 69 is expected to decrease from 55% to 44%. The proportion of ER+ invasive cancers is expected to remain the same near 63%, whereas the proportion of ER+ in-situ cancers is expected to increase from 19% to 29%. The proportion of ER- cancers (invasive and in-situ) is expected to decrease from 17% to 9%.

CONCLUSIONS: Breast cancer will continue to rise in the US through 2030, especially for ER+ in-situ tumors among older women. In contrast, ER- invasive and in-situ tumors will continue to fall. These results highlight a need to optimize case management among older women, and to better understand etiological factors responsible for declining ER- incidence rates.

Citation Format: Philip S. Rosenberg, Kimberly A. Barker, William F. Anderson. Estrogen receptor status and the future burden of invasive and in-situ breast cancers in the United States. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3699. doi:10.1158/1538-7445.AM2015-3699