Effect of Breast Conservation Therapy vs Mastectomy on Overall Survival and Breast Cancer-Specific Survival Among Men With Stage I-II Breast Cancer: Analysis of SEER, 2000-2018.

Background: Male breast cancer is a rare malignant tumor, and outcomes of breast conservation therapy (BCT) are currently lacking.
Method: The retrospective, population-based cohort study included 1369 stage I-II (T1-2 N0-1 M0) male breast cancer patients from the SEER database (2000-2018). The patients were grouped in two groups: BCT group and mastectomy group, according to surgical and radiation therapy. Kaplan-Meier method and univariable Cox proportional hazard analysis were used to compare overall survival (OS) and breast cancer-specific survival (BCSS) between two treatment groups. Propensity score matching (PSM) was performed to balance the confounding factors.
Results: Of the 1369 men, 97 (7%) patients received BCT, 1272 (93%) received mastectomy alone. The 5- and 10-year OS rates were 92.3% and 80.7% for BCT group compared with 80.4% and 61.4% for mastectomy group. The 5- and 10-year BCSS rates were 96.5% and 93.9% for patients undergoing BCT, as compared with 93.1% and 84.4% for patients undergoing mastectomy. Compared with mastectomy group, BCT group showed improved OS (hazard ratio [HR], 0.294; 95% CI 0.138-0.623, P = .002) and BCSS (hazard ratio [HR], 0.182; 95% CI 0.040-0.820, P = .027). Of the 791 patients with T1 stage, BCT showed insignificant association with OS (hazard ratio [HR], 0.555; 95% CI 0.207-1.488, P = .242) and BCSS (hazard ratio [HR], 1.217; 95% CI 0.171-8.675, P = .844).
Conclusion: The results of this cohort study suggest that BCT is at least equivalent to mastectomy in male breast cancer patients. The underlying mechanism of this association needs further research.
Competing Interests: Disclosure All other authors state that they have no conflicts of interest.
(Copyright © 2022. Published by Elsevier Inc.)