Abstract C108: Race and risk of subsequent aggressive breast cancer in women with ductal carcinoma in situ

Abstract

Abstract Background: Ductal carcinoma in situ (DCIS) is a heterogeneous group of preinvasive neoplastic lesions in the breast. Black women with DCIS are more likely than White counterparts to subsequently develop invasive cancer in either breast. We examined the association between race and the risk of developing aggressive invasive breast cancer, characterized with hormone receptor (HR) negativity (both estrogen receptor and progesterone receptor negative) or intermediate-to-high risk Oncotype scores (≥18) in HR-positive subtypes, in women with DCIS. Methods: Using the Surveillance, Epidemiology, and End Results (SEER) data, we identified 133,705 women with DCIS diagnosed between 1990 and 2015, and 12.9% were black. Cox proportional hazards regression was used to estimate relative risks (RRs) of subtypes of subsequent invasive breast cancer in either breast and metastatic breast cancer. Results: During a median follow-up of 90 months, 6889 women developed invasive breast cancer and 6384 had HR status available. The risks of HR-defined (Pheterogeneity=0.0004) and Oncotype score-defined (Pheterogeneity=0.046) invasive breast cancer subtypes after initial DCIS significantly varied by race. The RR of HR-negative invasive breast cancer was 1.86 (95% CI 1.57-2.20) and the RR of subsequent invasive subtypes with intermediate-to-high Oncotype scores was 1.29 (95% CI 1.00-1.67) in Black women with DCIS, which was independent of age, pathologic features and treatment. In women who had data on HR status in both primary DCIS and subsequent invasive breast cancer, the HR discordant rate was higher in Black patients than in White patients (21.2% versus 18.9%, P=0.003), which was largely driven by HR loss (15.4% versus 9.5%). Black race was more strongly associated with HR loss (RR=1.92, 95% CI 1.41-2.61, Pheterogeneity=0.03) than HR concordance (RR=1.24, 95% CI 1.09-1.41) and HR gain (RR=1.04, 95% CI 0.67-1.62). Conclusions: Black women with DCIS had higher risks of developing aggressive invasive breast cancer compared with White counterparts, which may contribute to their worse survival. Future studies examining biologic differences in the progression of DCIS for Black patients are warranted. Citation Format: Ying Liu, Graham Colditz. Race and risk of subsequent aggressive breast cancer in women with ductal carcinoma in situ [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr C108.