Effect of postmastectomy radiotherapy on T1-2N1M0 triple-negative breast cancer

Background The effect of postmastectomy radiotherapy (PMRT) on T1-2N1M0 triple-negative breast cancers (TNBC) remains unclear. The population-based study aimed to investigate the survival outcomes of T1-2N1M0 TNBC patients who underwent PMRT or not. Methods We selected 1743 patients with T1-2N1M0 TNBC who underwent mastectomy between 2010 and 2015 through the Surveillance, Epidemiology and End Results (SEER) database. After propensity score matching (PSM), the PMRT and no-PMRT groups consisted of 586 matched patients, respectively. The Kaplan-Meier method was applied to calculate breast cancer-specific survival (BCSS) and cox proportional hazard model was used to determine the prognostic factors of T1-2N1M0 TNBC. Results The 5-year BCSS for the PMRT and no-PMRT groups was 79.1% and 74.7%, respectively. Analysis showed that in patients with three nodes positive, radiotherapy could significantly improve BCSS (HR = 0.396, 95% CI = 0.175-0.900, P= 0.027), but it brought no significant advantage in BCSS in patients with one or two nodes positive (HR = 1.061, 95% CI = 0.725-1.552, P= 0.761; HR = 0.657, 95% CI = 0.405-1.065, P= 0.088). In addition, PMRT improves the BCSS in TNBC patients with T2 tumor concomitant with three positive lymph nodes (HR = 0.343, 95% CI = 0.132-0.890, P= 0.028). Conclusion TNBC patients with T2 tumor concomitant with three positive lymph nodes can benefit from PMRT.

Automated summary

The study aimed to investigate the survival outcomes of T1-2N1M0 TNBC patients who underwent PMRT or not, using data from the SEER database. Results showed that radiotherapy significantly improved BCSS in patients with three positive lymph nodes, but did not provide significant advantage in those with one or two positive lymph nodes. Additionally, PMRT was beneficial for TNBC patients with T2 tumors and three positive lymph nodes in terms of BCSS.