Abstract: Objective To investigate the effect of postmastectomy radiotherapy (PMRT) in patients with pathologically node-positive, stage T1-2N1M0 breast cancer after neoadjuvant chemotherapy (NAC) and mastectomy with ypN0. Methods A total of 187 pathologically node-positive, stage T1-2N1M0 breast cancer patients treated with NAC and modified radical mastectomy with and without PMRT who achieved ypN0 were retrospectively analyzed in our institution from 2003 to 2013. Patients all received fine needle aspiration biopsy (FNAB) of axillary nodes before NAC. Patients were divided into PMRT group (n=81) and NO PMRT group (n=106) according to whether they received postoperative radiotherapy for breast cancer. Statistical analyses were conducted using Chi-square test, Fisher exact test, Kaplan-Meier method, log-rank test and Cox proportional hazards regression model. Results DFS and DMFS were significantly improved in the PMRT group (P＜0.05), but there was no significant difference between the LRFFS and OS groups (P＞0.05). The prognosis of DMFS and DFS was better in patients with earlier pathological T stage, PMRT and age ≥ 40 years after NAC (P＜0.05). Patients with soft tissue involvement showed a poor prognosis (P＜0.05). Conclusion Patients with pathologically node-positive, stage T1-2N1M0 breast cancer, completed nodal response to NAC and received following modified radical mastectomy with ALND show comparatively good prognosis. PMRT could increase DFS and DMFS but have a marginal effect on LRR or OS in this study.

Key words: breast neoplasms, neoadjuvant treatment, mastectomy, modified radical, radiotherapy, adjuvant, prognosis