Role of postmastectomy radiation therapy in breast cancer patients with different pathological responses to neoadjuvant chemotherapy

Objective The purpose of the present study was to investigate the role of postmastectomy radiation therapy (PMRT) after neoadjuvant chemotherapy in breast cancer patients of clinical stage II–III with different pathological responses to neoadjuvant chemotherapy. Methods We retrospectively analyzed 79 clinical stage II–III breast cancer patients who underwent mastectomy after neoadjuvant chemotherapy between 2008 and 2013. According to the Miller–Payne grading system, we defined grades 1–2 as the poor response group, and grades 3–5 as the good response group. The 5‐year curves for locoregional recurrence free survival (LRRFS), distant disease‐free survival, and overall survival were constructed using the Kaplan–Meier method, and compared using the log–rank test. Results For all patients, the median age was 48 years (range 29–68 years). At a median follow up of 56 months, the 5‐year LRRFS was 97.8% and 81.8% (P = 0.01), the 5‐year distant disease‐free survival was 73.9% and 75.8% (P = 0.14), and the 5‐year overall survival for both was 84.8% (P = 0.96). In the subgroup analysis, the LRRFS, distant disease‐free survival, and overall survival of the subgroup with a good response did not benefit from PMRT. However, the LRRFS of the poor response subgroup can significantly benefit from PMRT (P = 0.04). Conclusions PMRT was effective in reducing the local‐regional recurrence rate for patients with a Miller–Payne grade 1–2; therefore, we suggest that PMRT should be considered for these patients.