Possible benefits from post-mastectomy radiotherapy in node-negative breast cancer patients: a multicenter analysis in Korea (KROG 14-22).

Hae Jin Park,Hyun Soo Shin,Kyung Ran Park,Bae Kwon Jeong,Yong Bae Kim,Yeon-Joo Kim,Kyubo Kim,Sun Young Lee,Kyung Hwan Shin,Su Ssan Kim,Jin Hee Kim,Seung Do Ahn,Jin Ho Kim,Won Park

doi:10.18632/oncotarget.16241

Abstract

PurposeThis study was performed to identify a subset of patients who may benefit from post-mastectomy radiotherapy (PMRT) among node-negative breast cancer patients.Materials and MethodsWe retrospectively reviewed 1,828 patients with pT1-2N0 breast cancer, treated with mastectomy without PMRT from 2005 to 2010 at 10 institutions. Univariate and multivariate analyses for locoregional recurrence (LRR) and any first recurrence (AFR) were performed according to clinicopathologic factors and biologic subtypes.ResultsDuring a median follow-up period of 5.9 years (range: 0.7-10.4 years), 98 patients developed AFR (39 isolated LRR, 13 LRR with synchronous distant metastasis, and 46 isolated distant metastasis), and 52 patients developed LRR. The 7-year LRR and AFR rates were 3.8% and 6.7%, respectively. Multivariate analysis revealed that age of ≤ 40 years (p<0.001) and T2 stage (p=0.013) were independent risk factors for LRR. The 7-year LRR rates were 2.5% with no risk factors, 4.5% with one risk factor, and 12.4% with two risk factors. Multivariate analysis for AFR revealed that age of ≤ 40 years (p<0.001), T2 stage (p<0.001), and triple-negative biological subtype (p=0.045) were independent risk factors for AFR. The 7-year AFR rates were 3.9% with no risk factors, 8.4% with one risk factor, and 15.7% with two to three risk factors.ConclusionsMastectomy without PMRT is a sufficient local treatment for pT1-2N0M0 breast cancer. Nevertheless, PMRT might be considered for patients with two or three risk factors, among those of young age, with T2 tumors, and with the triple-negative biological subtype based on LRR and AFR.

Highlights

There is a consensus that post-mastectomy radiotherapy (PMRT) is indicated for the breast cancer with locally advanced disease (T3-T4), or four or more positive axillary lymph nodes (LNs) [1, 2]
The purpose of this study was to identify the risk factors for locoregional recurrence (LRR) and any first recurrence (AFR) in node-negative patients treated with mastectomy but not PMRT, defining a subgroup of patients who may benefit from PMRT
The present study showed that the 7-year overall incidence of LRR was 3.8% in patients with pT1-2N0 breast cancer treated with mastectomy but not PMRT

Summary

Introduction

There is a consensus that post-mastectomy radiotherapy (PMRT) is indicated for the breast cancer with locally advanced disease (T3-T4), or four or more positive axillary lymph nodes (LNs) [1, 2]. Based on the results of a recent meta-analysis [3], PMRT can be applied to one to three positive axillary LNs. On the other hand, mastectomy is generally considered a sufficient local treatment method for nodenegative breast cancer. As the understanding of the molecular biology of breast cancer improves, the biological subtype is receiving attention as a possible prognostic factor with which to distinguish patients with a high versus low risk of local recurrence [5,6,7]. The purpose of this study was to identify the risk factors for locoregional recurrence (LRR) and any first recurrence (AFR) in node-negative patients treated with mastectomy but not PMRT, defining a subgroup of patients who may benefit from PMRT

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