Overall survival (OS) of men and women with breast cancer according to tumor subtype: A population-based study.

Abstract

1069 Background: The outcomes of male breast cancer (MBC) and female breast cancer (FBC) according to tumor subtype are poorly known. Our group previously reported the prognostic significance of tumor subtypes in MBC. The aim of this study was to analyze differences in OS between MBC and FBC according to tumor subtype compared with other factors. Methods: We evaluated men and women with microscopically confirmed invasive breast cancer between 2010 and 2013 with known estrogen receptor (ER) and progesterone receptor (PR) (together hormone receptor [HR]) status and human epidermal growth factor receptor 2 (HER2) status reported to the SEER program. Patients (pts) with other primary either before or after breast cancer were excluded. Pt characteristics were compared between MBC and FBC. Univariate and multivariate analyses were performed to determine the effect of each variable on OS. Results: We included 1,187 MBC and 166,054 FBC pts. Median age for MBC was 65 years (range 26-97) and for FBC was 60 years (range 18-108). Median follow-up was 21 months (range 1-48) for both groups. OS at 3 years for MBC and FBC was 85.6% and 90.4%, respectively (p = 0.0002). MBC pts were more frequently ductal, had higher grade, presented with more advanced stage and were more often HR+/HER2- (all p < 0.0001). MBC had worse OS than FBC in HR+/HER2- (Hazard ratio [HaR] 1.5; p = 0.0005), HR+/HER2+ (HaR 2.8; p < 0.0001) and triple negative (TN) (HaR 4.3; p < 0.0001) (p for interaction < 0.02). MBC had significantly worse OS than FBC in stage I and II, but similar OS in stage III and IV (p for interaction < 0.01). In multivariate analysis adjusted for age, race, grade, stage, surgery, radiation and marital status; HR+/HER2+ was the only subtype with significant differences in OS between MBC and FBC (HaR 2.0; p = 0.002). Conclusions: In this cohort, we observed significant differences in the distribution of tumor subtypes between MBC and FBC. OS was significantly different in both groups. Men had worse OS in stage I and II while similar OS in stage III and IV. There were significant differences in OS according to tumor subtype; compared with women, men with HR+/HER2+ tumors had twice the risk of death.