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.
Methods: In 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.
Results: The 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.
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.