Abstract 5276: Risk factors for ductal carcinoma in situ of the breast in African American women

Introduction: The clinical significance of a ductal carcinoma in situ (DCIS) diagnosis is uncertain. While overall breast cancer mortality risk from DCIS is very low, a recent analysis showed that African American women diagnosed with DCIS were more than twice as likely to die from breast cancer as U.S. white women. Elucidation of risk factors for DCIS in African American women may provide opportunities for risk reduction. Methods: To assess the relation of reproductive, anthropometric, and other factors to risk of DCIS in African American women, we pooled data from three epidemiologic studies participating in the African American Breast Cancer Epidemiology and Risk (AMBER) Consortium - the Black Women’s Health Study, the Carolina Breast Cancer Study, and the Women’s Circle of Health Study. These studies contributed 805 DCIS cases and 13,830 controls to the analysis. We used unconditional logistic regression models to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for risk of DCIS in relation to each risk factor of interest. Multivariable models were used to mutually adjust for risk factors as well as matching factors (age, study, geographic region, and questionnaire time period). We also compared results to associations observed for invasive breast cancer (n=3,765). Results: First degree family history of breast cancer was associated with an increased risk of DCIS (OR 1.62, 95% CI 1.32, 1.98). Oral contraceptive use within the past 10 years (vs. never) was also associated with increased risk (OR 1.31, 95% CI 1.01, 1.70), as was late age at first birth (≥25 years vs.