Abstract
PURPOSE: Current treatment guidelines for male breast cancer are guided by female-only trials despite data suggesting distinct clinicopathologic differences between sexes. We sought to evaluate whether radiation therapy (RT) after lumpectomy was associated with equivalent survival among men > 70 years of age with stage I, estrogen receptor (ER) positive tumors, as seen in women from the Cancer and Leukemia Group B (CALGB) 9343 trial. METHODS: We performed a retrospective analysis of 752 stage I, ER-positive male breast cancer patients ≥ 70 years who were treated with hormone therapy and surgery, with or without RT, from the National Cancer Database between 2004 and 2014. Patients were categorized based on surgery and RT (lumpectomy alone, lumpectomy with RT, and mastectomy alone). Multivariable Cox proportional hazards regression analysis was used to compare overall survival between treatment groups. RESULTS: Most patients underwent total mastectomy, with only 32.6% treated with lumpectomy. Of those who underwent lumpectomy, 72.7% received adjuvant RT. In multivariate analysis, there was no statistical difference in overall survival when comparing lumpectomy alone and lumpectomy with RT (aHR 0.72 [95% CI 0.38-1.37], p = 0.31) or when comparing lumpectomy (alone or with RT) and mastectomy (aHR 1.28 [95% CI 0.88-1.87], p = 0.20). CONCLUSIONS: In this national sample of elderly men with ER-positive early-stage disease treated with endocrine therapy, there were no significant differences in overall survival when comparing lumpectomy alone and lumpectomy with RT, or lumpectomy (alone or with RT) and mastectomy. These results suggest that less aggressive treatment may be appropriate for a subset of male breast cancer patients.