l Contraceptive Use and Estrogen / Progesterone eptor – Negative Breast Cancer among B & P can American Women

Downlo kground: Oral contraceptive formulations have changed over time, making it relevant to assess the of more recent formulations on breast cancer risk. In addition, some studies have found stronger posisociations of oral contraceptive use with estrogen receptor–negative (ER) than with ER-positive (ER) cancer. We carried out the first assessment of the effect of oral contraceptive use on the incidence of cancer classified by receptor status among African American women, a group disproportionately afby ER cancer. thods:We followed 53,848 Black Women's Health Study participants from 1995 to 2007 through biennial questionnaires, in which participants reported information about incident breast cancer, oral contrae use, and breast cancer risk factors. Pathology information was obtained on receptor status for 789 nt cases. Incidence rate ratios (IRR) with 95% confidence intervals (95% CI) were derived from Cox sion models with control for confounding factors. ults: Ever use of oral contraceptives was more strongly associated with ERPR breast cancer (279 IRR, 1.65; 95% CI, 1.19-2.30) than with ERPR cancer (386 cases; IRR, 1.11; 95% CI, 0.86-1.42). The risk PR breast cancer increased with increasing duration of use among recent users. clusions: These results indicate that the oral contraceptive formulations used in recent decades increase cancer risk in African American women, with a greater effect for ER than ER cancer. breast Impact:Mechanisms to explain the adverse influence of oral contraceptive use on ER breast cancer need to be elucidated. Cancer Epidemiol Biomarkers Prev; 19(8); 2073–9. ©2010 AACR.