Postmastectomy Radiotherapy Improves Disease-Free Survival of High Risk of Locoregional Recurrence Breast Cancer Patients with T1-2 and 1 to 3 Positive Nodes

OBJECTIVES: The indications for post-mastectomy radiotherapy (PMRT) with T1-2 breast cancer and 1-3 positive axillary lymph nodes is still controversial. The purpose of this study was to investigate the role of PMRT in T1-2 breast cancer with 1-3 positive axillary lymph node. METHODS: We retrospectively reviewed the file records of 79 patients receiving PMRT and not receiving PMRT (618 patients). RESULTS: The median follow-up was 65 months. Multivariate analysis showed that PMRT was an independent prognostic factor of locoregional recurrence-free survival (LRFS) (P = 0.010). Subgroup analysis of patients who did not undergo PMRT showed that pT stage, number of positive axillary lymph nodes, and molecular subtype were independent prognostic factors of LRFS. PMRT improved LRFS in the entire group (P = 0.005), but did not affect distant metastasis-free survival (DMFS) (P = 0.494), disease-free survival (DFS) (P = 0.215), and overall survival (OS) (P = 0.645). For patients without PMRT, the 5-year LRFS of low-risk patients (0–1 risk factor for locoregional recurrence) of 94.5% was significantly higher than that of high-risk patients (2-3 risk factors for locoregional recurrence) (80.9%, P < 0.001). PMRT improved LRFS (P = 0.001) and DFS (P = 0.027) in high-risk patients, but did not improve LRFS, DMFS, DFS, and OS in low-risk patients. CONCLUSIONS: PMRT is beneficial in patients with high risk of locoregional recurrence breast cancer patients with T1-2 and 1 to 3 positive nodes.