BACKGROUND AND OBJECTIVEThe 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.

METHODSIn the retrospective data of 488 eligible patients, survival analysis was performed using the Kaplan-Meier method. Univariate and multivariate analyses were performed using a log-rank test and the Cox proportional hazards model, respectively.

RESULTSThe median observation time was 54 months. The 5- and 10-year locoregional recurrence-free 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) receptor-negative 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 10-year 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.

CONCLUSIONSIn 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.