Biological subtype predicts locoregional recurrence after postmastectomy radiotherapy in Chinese breast cancer patients

Abstract

Aim: To investigate the impact of biological subtypes in locoregional recurrence in Chinese breast cancer patients receiving postmastectomy radiotherapy (PMRT). Methods and Materials: About 583 patients who received postmastectomy radiation between 2010 and 2012 were retrospectively analyzed. According to immunohistochemical staining profile, patients were classified into: Luminal A-like, Luminal B-like, HER2-positive, and triple-negative breast cancer (TNBC). Local and regional recurrence (LRR) cumulative incidences were calculated by competing risks methodology and the power of prognostic factors was examined by Gray's test and the test of Fine and Gray. Results: The median follow-up was 70.9 months. About 34 LRR events occurred. For Luminal A, Luminal B, HER2-positive, and TNBC patients, the 5-year LRR cumulative incidence rates were 1.57%, 4.09%, 10.74%, and 10.28%. Compared with Luminal A, HER2-positive subtype and TNBC had a significant increased risk of LRR (HR was 5.034 and 5.188, respectively). In univariate analysis, predictive factors for higher LRR were HER2-positive subtype (HR = 4.43, P .05) in HER2-positive subtype patients, while LRR with trastuzumab was approximate to Luminal A (with vs Luminal A, P >.05). Additionally, endocrine therapy also significantly reduced LRR incidence in the luminal subtype cohort (without vs with therapy, 6.25% vs 2.89%, HR = 0.365, P