Factors associated with twenty-year (y) risks of breast cancer-specific mortality (BCSM) in the Surveillance, Epidemiology, and End Results (SEER) Registry.

Abstract

540 Background: Most reports describing the risk of late relapse in breast cancer have been based on selected patients (pts) enrolled into clinical trials. The aims of this study were to report on population-based long-term risks of BCSM, and the risks of BCSM conditional on having survived 5 y. Additionally, we aimed to identify factors associated with late deaths from breast cancer. Methods: Using SEER data, we identified women with breast cancer (T1-T2, N0-N2, M0) between 1990-2005, with one primary cancer in their lifetime, and known hormone receptor (HR) status. We used Kaplan-Meier analyses to determine the effect of baseline variables on cumulative risks of BCSM, we estimated annual rate of events per 100 person-years, and performed Cox regression stratified by HR status. Results: We included 202,080 pts (median follow-up = 12.25 y). Of all breast cancer deaths, the proportion after 5 y was 65% for HR+ vs 28% for HR- (p < 0.001). The table shows risks of BCSM by HR and N status, and annual event rates. The cumulative risk of BCSM in y 5-20 ranged from 7.9% in HR-N0 to 38% in HR+N2. Among HR+ pts, adjusted risks of BCSM conditional on having survived 5 y were higher for T2 vs T1a (Hazard ratio [HzR] 3.3, p < 0.001), N2 vs N0 (HzR 3.5, p < 0.001), age at diagnosis (dx) > 64 y vs < 50 y (HzR 1.4, p < 0.001), black race vs white (HzR 1.3, p < 0.001) and grade III vs I (HzR 2.3, p < 0.001). For HR- pts, adjusted risks of BCSM conditional on having survived 5 y were higher for T2 vs T1a (HzR 2.0, p < 0.001), N2 vs N0 (HzR 2.8, p < 0.001) and age at dx > 64 y vs < 50 y (HzR 1.6, p < 0.001). Conclusions: For HR+ breast cancer, risks of BCSM remain high beyond 5 y from dx and depend on T-N status, age, race and grade. In HR- breast cancer, the risk of BCSM is highest within 5 y from dx; however, risks beyond 5 y are still considerable and depend on T-N status and age. Our results underscore the need for better adjuvant therapies in both HR+ and HR- breast cancer. [Table: see text]