To analyze differences in overall survival (OS) between male breast cancer (MBC) and female breast cancer (FBC) according to tumor subtype compared with other factors.
We evaluated men and women with breast cancer between 2010 and 2013 with known hormone receptor (HR) status and human epidermal growth factor receptor 2 (HER2) status reported to the National Cancer Institute’s Surveillance, Epidemiology, and End Results program. Patient characteristics were compared between groups. Univariate and multivariate analyses were performed to determine the effect of each variable on OS. Breast cancer–specific survival was a secondary endpoint.
We included 1187 MBC and 166,054 FBC. Median follow-up was 21 months (range, 1 to 48) for both groups. OS at 3 years for MBC and FBC was 85.6% and 90.4%, respectively (P=0.0002). MBC were more ductal, had higher grade, presented with more advanced stage and were often HR+/HER2− (each 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 (HaR, 4.3; P<0.0001) (P interaction<0.02). MBC had significantly worse OS than FBC in stages I and II, but similar OS in stages III and IV (P interaction<0.01). In multivariate analysis, HR+/HER2+ was the only subtype with significant differences in OS between MBC and FBC (HaR, 2.0; P=0.002).
OS was significantly different in both groups. Men had worse OS in early stages while similar OS in stages 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.
*Grupo Oncológico Cooperativo del Sur (GOCS)
†Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
‡Department of Medical Oncology, Breast Oncology Program, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA
Presented in part at the 2017 Annual Meeting of the American Society of Clinical Oncology: abstract 1069.
J.P.L. reports that the institution (University of Iowa) received research funds from Merck. The remaining authors declare no conflicts of interest.
Reprints: José P. Leone, MD, Dana-Farber Cancer Institute, 450 Brookline Ave, Boston, MA 02215. E-mail: firstname.lastname@example.org.