Background and Objective:The role of postmastectomy radiotherapy(PMRT) in breast cancer patients with T1-T2 tumors and 1-3 positive axillary nodes is still uncertain.This study investigated the value of PMRT for these patients.Met hods:In the retrospective data of 488 eligible patients,survival analysis was performed using the KaplanMeier method.Univariate and multivariate analyses were performed using a log-rank test and the Cox proportional hazards model,respectively.Result s:The median observation time was 54 months.The 5-and 10-year locoregional recurrencefree survival(LRFS) rates were 90.8% and 86.9%,respectively.The 5-and 10-year disease-free survival(DFS) rates were 82.0% and 74.3%,respectively.The 5-and 10-year overall survival(OS) rates were 90.7% and 82.7%,respectively.For the 412 patients without PMRT,T2 classification,2-3 positive nodes,and hormone(estrogen and progesterone) receptornegative were risk factors for locoregional recurrence in the multivariate analysis.On the basis of these 3 risk factors,the group with 2-3 factors had a 10-year LRFS rate of 63.1% compared with 96.1% for the group with 0-1 factors(P < 0.001).For the group with 2-3 risk factors,LRFS and DFS were significantly improved by PMRT,with the 5-and 10-year LRFS rates without PMRT of 82.4% and 63.1%,respectively,and,with PMRT,of 98.1% at both 5 years and 10 years(P = 0.002).The 5-and 10-year DFS rates without PMRT were 72.0% and 57.6%,respectively,and,with PMRT,the 5-and 10year DFS rates were 89.4% and 81.7%,respectively(P = 0.007).There was no significant difference in the 10-year OS rates between patients with and without PMRT.However,there is the potential benefit of 15.3%(87.1% vs.71.8%,P = 0.072).Conversely,the group with 0-1 factors of PMRT had no effect on prognosis.Conclusions:In patients receiving mastectomy with T1-T2 breast cancer with 1-3 positive nodes,for the group with 2-3 risk factors,PMRT significantly improved LRFS and DFS and has potential benefit in OS. Background and Objective: The role of postmastectomy radiotherapy (PMRT) in breast cancer patients with T1-T2 tumors and 1-3 positive axillary nodes is still uncertain. This study investigated the value of PMRT for these patients. Met hods: In the retrospective data of 488 eligible patients, survival analysis was performed using the Kaplan Meier method. Univariate and multivariate analyzes were performed using a log-rank test and the Cox proportional hazards model, respectively. Results s: The median observation time was 54 months. The 5-and The 10-year locoregional recurrence survival (LRFS) rates were 90.8% and 86.9% respectively. The 5-and 10-year disease-free survival Overall survival (OS) rates were 90.7% and 82.7%, respectively. For the 412 patients without PMRT, T2 classification, 2-3 positive nodes, and hormone (estrogen and progesterone) receptornegative were risk factors for locoregional recurrence in the multivariate analysis. On the b as the group of 3 risk factors, the group with 2-3 factors had a 10-year LRFS rate of 63.1% compared with 96.1% for the group with 0-1 factors (P <0.001) .For the group with 2-3 risk Factors, LRFS and DFS were significantly improved by PMRT, with the 5-and 10-year LRFS rates without PMRT of 82.4% and 63.1%, respectively, and with PMRT, of 98.1% at both 5 years and 10 years (P = 0.002). The 5-and 10-year DFS rates without PMRT were 72.0% and 57.6%, respectively, and with PMRT, the 5- and 10-year DFS rates were 89.4% and 81.7%, respectively (P = 0.007) was no significant difference in the 10-year OS rates between patients with and without PMRT. There was a potential benefit of 15.3% (87.1% vs.71.8%, P = 0.072) .Conversely, the group with 0-1 factors of PMRT had no effect on prognosis. Conclusions: In patients receiving mastectomy with T1-T2 breast cancer with 1-3 positive nodes, for the group with 2-3 risk factors, PMRT significantly improved LRFS and DFS and has potential benefit in OS.