Postmastectomy radiation therapy for T3N0: a SEER analysis.

BACKGROUND: There is conflicting evidence regarding the benefit of postmastectomy radiation therapy (PMRT) for pathologic stage T3N0M0 breast cancers. We analyzed data from the Surveillance, Epidemiology, and End Results (SEER) database to investigate the benefit of PMRT in this patient population. METHODS: We queried the SEER database for T3N0M0 breast cancer patients diagnosed from 2000 to 2010 who underwent modified radical mastectomy. We excluded males, patients with unknown radiation timing/type, other primary tumors, and survival <6 months. A total of 2525 patients were included in the analysis. We performed univariate and multivariate statistical analysis using chi-square tests, log-rank tests, and Cox proportional hazards regression. The primary endpoints were overall survival (OS) and cancer-specific survival (CSS). RESULTS: Of the 2525 patients identified, 1063 received PMRT. The median follow-up was 56 months (range, 6-131 months). On univariate analysis, PMRT improved OS (76.5% vs 61.8%, P<.01) and CSS (85.0% vs 82.4%, P<.01) at 8 years. The use of PMRT remained significant on multivariate analysis: PMRT improved OS (hazard ratio 0.63, P<.001) and CSS (hazard ratio 0.77, P = .045). Low tumor grade (P<.01) and marital status of "married" (P = .01) also was a predictor of improved CSS on multivariate analysis. CONCLUSIONS: PMRT was associated with significant improvements in both CSS and OS in patients with T3N0M0 breast cancers treated with modified radical mastectomy from 2000 to 2010. PMRT should be strongly considered in T3N0M0 patients. Postmastectomy radiation therapy is associated with significant improvements in overall and cause-specific survival in patients with T3N0M0 breast cancers treated with modified radical mastectomy from 2000 to 2010 in the SEER database. Postmastectomy radiation therapy should be strongly considered for patients who have T3N0M0 tumors.