Flanders, Dana

Abstract Identifying risk factors for women at high risk of symptom-detected breast cancers that were missed by screening would enable targeting of alternative prevention strategies. To identify breast cancer risk factors by mode of detection, we examined these associations in heavily-screened women from the Cancer Prevention Study (CPS)-II Nutrition Cohort. Among 76,406 women followed for a median of 13.8 years, 2,469 screen-detected and 1,189 symptom-detected breast cancer cases were diagnosed. Multivariable-adjusted associations were estimated using joint Cox proportional hazards regression models with person-time calculated contingent on screening. The mean (standard deviation) age at baseline was 62.0 (6.6) years for non-cases, 61.6 (6.1) for screen-detected cases, and 61.5 (6.2) for symptom-detected cases. Women with symptom-detected tumors were diagnosed at a slightly younger age (mean=69.4) and less likely to be diagnosed with a localized tumor (65.3%), than women with a screen-detected tumor (mean age at diagnosis=70.4 and localized tumors=83.3%). Factors associated with higher risks of symptom detected vs. screen detected breast cancer, included: current combined menopausal hormone use (HR=2.04, 95% CI 1.70 - 2.46 vs. HR=1.43, 95% CI 1.25 - 1.63), current estrogen only menopausal hormone use (HR=1.41, 95% CI 1.15 - 1.72 vs. HR=0.94, 95% CI 0.82 - 1.09), and history of benign breast disease (HR=1.89, 95% CI 1.67 - 2.13 vs. HR=1.49, 95% CI 1.36 - 1.62). The opposite pattern of higher risk of screen detected vs. symptom detected breast cancer was observed for greater adult weight gain (HR=2.32, 95% CI 1.91 - 2.82 vs. HR=1.42, 95% CI 1.10 - 1.84) and alcohol intake (HR=1.39, 95% CI 1.24 - 1.64 vs. HR=1.20, 95% CI 0.92 - 1.58). Our results suggest that understanding risk factors for symptom-detected cancers may help identify women who would benefit from more intensive screening to facilitate early detection. Citation Format: Mia M. Gaudet, Emily Deubler, W. Ryan Diver, Samantha Puvanesarajah, Alpa V. Patel, Ted Gansler, Dana Flanders, Mark Sherman, Susan Gapstur. Breast cancer risk factors by mode of detection among screened women in the Cancer Prevention Study-II [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4211.