Racial and ethnic disparities in mortality among breast cancer survivors after a second malignancy


 
 
 Racial and ethnic differences in survival after a first cancer are well established but have not been examined after a SPC despite the increasing incidence among survivors.
 
 
 
 We examined 39,029 female breast cancer survivors who developed a SPC between 2000-2014 in the Surveillance, Epidemiology, and End Results (SEER) 18 database. Multivariable Cox proportional hazard regression for competing risks data was used to estimate hazard ratio (HR) and 95% confidence interval (CI) for cancer and cardiovascular disease (CVD) mortality after SPCs comparing Hispanic, Non-Hispanic Asian, and Non-Hispanic Black survivors to Non-Hispanic White survivors. Models were adjusted for sociodemographic, tumor characteristics, and treatments of the first and second cancer. Analyses were stratified by SPC type.
 
 
 
 During 17 years of follow-up, there were 15,117 deaths after SPCs. The risk of cancer death was 12% higher among Non-Hispanic Black survivors (HR: 1.12, 95%CI: 1.05-1.19) and 8% higher among Hispanic survivors (HR: 1.08, 95%CI: 1.00-1.16) compared to Non-Hispanic White survivors. In subgroup analyses, the strongest associations were observed among Non-Hispanic Black survivors with a second breast or uterine cancer and among Hispanic survivors with a second breast cancer. Non-Hispanic Black survivors also experienced a 44% higher risk of CVD death after SPC diagnosis than Non-Hispanic White survivors (HR: 1.44, 95%CI: 1.20-1.74).
 
 
 
 Higher cancer mortality among Non-Hispanic Blacks and Hispanics and higher cardiovascular mortality among Non-Hispanic Blacks exist among women who survive a first breast cancer to develop a SPC. Studies focused on identifying the contributors to these disparities are needed to enable implementation of effective mitigation strategies.
