Adjuvant trastuzumab reduces locoregional recurrence in women who underwent mastectomy without radiation therapy for HER-2-positive breast cancer: a retrospective analysis with propensity score matching

Abstract

Objective To investigate the locoregional benefit from adjuvant anti-HER-2 target therapy and the possibility of omitting postmastectomy radiation therapy (PMRT) in HER-2 positive breast cancer patients. Methods Clinical data of 1398 patients diagnosed with HER-2+ breast cancer admitted to our hospital who underwent mastectomy without PMRT from 2009 to 2014 were retrospectively analyzed, and 370 of them received adjuvant anti-HER-2 target therapy mainly with trastuzumab. Results Anti-HER-2 target therapy significantly improved the disease-free survival (DFS) and overall survival (OS), whereas reduced the locoregional recurrence (LRR) insignificantly. Multivariate analysis demonstrated that anti-HER-2 target therapy improved the locoregional recurrence-free survival (LRRFS)(P=0.06). After propensity score matching, the 5-year LRR rate was 4.4% vs. 6.4%(P=0.070) for those treated with and without anti-HER-2 target therapy. Subgroup analysis revealed that the locoregional control benefit was only significant in patients with pathological Grade Ⅰ-Ⅱtumors (2.5% vs. 5.9%, P=0.046). For patients with pN1 tumors with and without anti-HER-2 target therapy, the 5-year LRR rate was 8.2% vs. 12.3%(P=0.150). Patients with hormone receptor-positive tumors obtained significant benefit from anti-HER-2 target therapy. The 5-year LRR rate could be less than 5% in patients with favorable risk factors who received anti-HER-2 target therapy. Conclusions Anti-HER-2 target therapy with trastuzumab can improve the LRRFS of patients with HER-2+ breast cancer after mastectomy. Nevertheless, patients with radiotherapy indications have to receive radiotherapy due to relatively high recurrence rate. Newly approved dual HER-2 blockade is a promising approach to further reduce LRR. Subgroup analysis is required to identify the low-risk patients. Key words: Breast neoplasm/target therapy; HER-2 gene; Locoregional recurrence; Locoregional recurrence-free survival