Racial differences in breast cancer, cardiovascular disease, and all-cause mortality among women with ductal carcinoma in situ of the breast

Ductal carcinoma in situ (DCIS) of the breast represents 15-20 % of new breast cancer diagnoses in the US annually. However, long-term competing risks of mortality, as well as racial differences in outcomes among US women with DCIS, are unknown. Case data from the years 1978-2010 were obtained using SEER*Stat software available through the National Cancer Institute from the 2010 SEER registries. Included were all women aged 40 and over with newly diagnosed DCIS. There were 67,514 women in the analysis, including 54,518 white women and 6,113 black women. A total of 12,173 deaths were observed over 607,287 person-years of follow-up. The 20-year cumulative incidence of all-cause death among women with DCIS was 39.6 % (CI 38.9-40.3). The corresponding 20-year rates for breast cancer death and CVD death were 3.2 % (CI 3.0-3.4) and 13.2 % (CI 12.8-13.7), respectively. Black women with DCIS had a higher risk of death compared to white women, with these hazard ratios elevated throughout the entire study period. For example, between 1990 and 2010, black women had a higher risk of all-cause death (HR 3.06, CI 2.39-3.91), breast cancer death (HR 5.78, CI 3.16-10.57), and CVD death (HR 6.43, CI 3.61-11.45) compared to white women diagnosed between 50 and 59 years of age. The risk of all-cause and CVD death was greater than breast cancer death among women diagnosed with DCIS over 20 years. Black women had higher risks of dying from all-causes compared to white women. These differences persisted into the modern treatment era.