Postmastectomy Radiotherapy After Neoadjuvant Chemotherapy in cT1-2N+ Breast Cancer Patients: A Single Center Experience and Review of Current Literature

PurposePostmastectomy radiotherapy (PMRT) after neoadjuvant chemotherapy (NAC) in breast cancer patients with initial clinical stage cT(1-2)N(+), especially for those who achieved ypT(1-2)N(0), is still controversial. This study was to evaluate the survival prognosis of cT(1-2)N(+) patients after NAC with or without PMRT, and to discuss the selection of patients who may omit PMRT. Patients and MethodsFrom January 2005 to December 2017, 3055 female breast cancer patients underwent mastectomy in our medical center, among whom 215 patients of cT(1-2)N(+) stage, receiving NAC with or without PMRT were finally analyzed. The median follow-up duration was 72.6 months. The primary endpoint was disease-free survival (DFS), and secondary endpoint was overall survival (OS). Comparison was conducted between PMRT and non-PMRT subgroups. ResultsOf the 215 eligible patients, 35.8% (77/215) cT(1-2)N(+) patients achieved ypT(0-2)N(0) after NAC while 64.2% (138/215) of the patients remained nodal positive (ypT(0-2)N(+)). The 5-year DFS of ypT(0-2)N(0) non-PMRT was 79.5% (95% confidence interval [CI] 63.4-95.6%). No statistically significant difference was observed between the ypT(0-2)N(0) PMRT and non-PMRT subgroups for the 5-year DFS (78.5% vs 79.5%, p = 0.673) and OS (88.8% vs 90.8%, p = 0.721). The 5-years DFS didn't obviously differ between the ypT(0-2)N(0) non-PMRT subgroup and cT(1-2)N(0) subgroup (79.5% vs 93.3%, p = 0.070). By using Cox regression model in multivariate analyses of prognosis in ypT(0-2)N(+) PMRT subgroup, HER2 overexpression and triple-negative breast cancer were significantly poor predictors of DFS and OS, while ypN stage was significant independent predictors of OS. ConclusionAn effective response to NAC (ypT(0-2)N(0)) indicates a sufficiently favorable prognosis, and PMRT might be omitted for cT(1-2)N(+) breast cancer patients with ypT(0-2)N(0) after NAC.