Purpose: There are no randomized studies on the indication for postmastectomy radiation therapy (PMRT) in patients who receive neoadjuvant chemotherapy (NAC) followed by a mastectomy. The aim of this study was to determine clinical outcomes and identify reliable prognostic factors in patients with locally advanced breast cancer treated with NAC followed by a mastectomy and PMRT.
Methods and materials: We retrospectively evaluated the relationship between clinicopathological factors and outcomes in 351 patients with stage II or III breast cancer who underwent NAC followed by radical mastectomy and PMRT between March 2005 and December 2013.
Results: The median follow-up duration was 81 months (Range, 12-156 months). For all patients, the 5-year locoregional recurrence-free survival (LRFS), distant metastasis-free survival (DMFS), and overall survival (OS) rates were 91.3 %, 69.8 %, and 83.4 %, respectively. On multivariate analysis, estrogen-receptor positivity, and complete response of cancer in axillary nodes (ypN0) were significant prognostic factors for better LRFS, while lympho-vascular invasion and clinical stage IIIC were independent prognostic factors for worse LRFS. The number of axillary node metastasesafter surgery was an independent prognostic factor of DMFS and OS. Patients with hormone receptor- and human epidermal growth factor receptor 2 positivity had significantly better 5-year LRFS rates.
Conclusions: We identified several prognostic factors in our study. In particular, the number of axillary node metastases is significantly related to OS.