Abstract B117: Risk factors of second breast cancer among patients with ductal carcinoma in situ

Abstract

Abstract Background: Women with ductal carcinoma in situ (DCIS) are at increased risk of breast cancer in either ipsilateral or contralateral breasts. However, it is inconclusive about the factors predicting the risk of second breast cancer after DCIS. Methods: We used US Surveillance, Epidemiology, and End Results data on women with first unilateral DCIS diagnosed between 1988 and 2009. Relative risks (RRs) were estimated using cox regression models to identify the factors associated with the risks of second DCIS and second invasive breast cancer (IBC). Results: Of the 74,285 eligible DCIS patients, 6,140 (8.3%) had subsequent breast cancer during 8.5 years of follow-up (714 ipsilateral DCIS, 2,003 ipsilateral IBC, 997 contralateral DCIS, and 2,426 contralateral IBC). Patients <50 years (RR=1.45; 95% confidence interval (CI), 1.29-1.64), black patients (RR=1.60; 95% CI, 1.39-1.83), patients with comedo DCIS (RR=1.19; 95% CI, 1.07-1.32), and patients with poorly differentiated DCIS (RR=1.45; 95% CI, 1.15-1.82) were more likely to develop ipsilateral breast cancer. Solid histologic type was more strongly associated with increased risk of ipsilateral IBC (RR=1.49; 95% CI, 1.12-1.99). The risk of contralateral breast cancer was increased among black women (RR=1.33; 95% CI, 1.16-1.52) and was decreased among young women and women with comedo DCIS, which was more obvious for contralateral IBC. Conclusion: The risk factors were different for second breast cancer in the ipsilateral breast and in the contralateral breast. Improved follow-up of young patients, black patients, patients with poorly differentiated DCIS, and patients with comedo or solid DCIS may reduce the risk of second IBC. Further investigations are needed to identify molecular features of DCIS that predict risk of second breast cancer and/or mediate racial and age differences in second cancer risk. Citation Format: Ying Liu, Graham Colditz. Risk factors of second breast cancer among patients with ductal carcinoma in situ. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research: Genetics, Biology, and Clinical Applications; Oct 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2013;11(10 Suppl):Abstract nr B117.