Is There a Role for Post-Mastectomy Radiotherapy for T1-2N1 Breast Cancers With Node-Positive Pathology After Patients Become Node-Negative Pathology Following Neoadjuvant Chemotherapy?

Qian Wang,Shikai Wu,Xiangying Meng,Li Zhu,Xiaowei Han,Jinyan Shi,Huiru Sun,Bing Sun,Puchun Er,Jingjing Zhao,Jingyang Zhu,Wencheng Zhang

doi:10.3389/fonc.2020.00892

Abstract

Purpose: To assess the benefit of post-mastectomy radiotherapy (PMRT) in breast cancer (BC) patients with T1-2N1M0 who developed pathologically negative lymph nodes (ypN0) after undergoing neoadjuvant chemotherapy (NAC) and mastectomy.Patients and Materials: Patients with T1-2 tumors and positive lymph node(s) who became pN0 after NAC and mastectomy were screened from our prospectively maintained database. The primary endpoint was recurrence-free survival (RFS), and the secondary endpoints were local recurrence-free survival (LRFS) and overall survival (OS). Propensity-score matching (PSM) was conducted for the comparison between PMRT and non-PMRT groups.Results: Of the 142 eligible patients, 110 (77.5%) received PMRT, and 32 (22.5%) did not. The median follow-up time was 72 months. Univariate analyses showed that the 5-year RFS, LRFS, and OS rates were 88.7, 94.5, and 96.1, respectively, with PMRT and 72.4, 90.1, and 95.0% without PMRT (p = 0.028; p = 0.151; p = 0.971). Multivariate analyses established PMRT as a significant prognostic factor for RFS rate (HR, 0.411; 95% CI, 0.175–0.968; p = 0.042). After a PSM analysis (64 in the PMRT group vs. 32 in the non-PMRT group), PMRT remained significant, with improved RFS in univariate and multivariate analysis (with 5-year RFS rates of 90.1 vs. 72.4%, respectively, p = 0.016; HR, 0.323, 95%CI, 0.115–0.913, p = 0.033). In the subgroup of 48 (33.8%) patients with pathologic complete responses (pCR, ypT0, and ypN0) after NAC, PMRT did not affect RFS (HR, 0.226; 95% CI, 0.034–1.500; p = 0.123).Conclusions: PMRT might benefit pT1-2N1M0 patients with pN0 after NAC. Patients with pCR might consider omitting PMRT. Prospective studies are needed to assess the effect of PMRT on this specific patient population.

Highlights

Neoadjuvant chemotherapy (NAC) is a standard of care for patients with locally advanced or inflammatory breast cancer and is increasingly used to treat patients who have an early stage of the disease [1, 2]
Stage II (T1-2N1M0) breast cancer patients who were diagnosed between January 2004 and December 2016 and who achieved pN0 after neoadjuvant chemotherapy were enrolled in this study
NAC is used frequently in the treatment of clinical stage II breast cancer, raising issues regarding the indications for radiotherapy after mastectomy

Summary

Introduction

Neoadjuvant chemotherapy (NAC) is a standard of care for patients with locally advanced or inflammatory breast cancer and is increasingly used to treat patients who have an early stage of the disease [1, 2]. The potential efficiency of downstaging challenges the standard indications for post-mastectomy adjuvant radiotherapy [3, 4]. It is unclear whether initial clinical stage or residual disease after NAC is the more important factor in predicting locoregional recurrence (LRR). According to findings from previous randomized trials, the use of post-mastectomy radiation therapy (PMRT) can improve the outcomes of selected patients who receive mastectomy in the adjuvant setting [5,6,7]. None of the prospective phase III trials conducted to date has investigated the effect of PMRT in patients who received neoadjuvant treatment. Selecting patients to undergo PMRT after NAC treatment is still contentious and has only followed directions suggested by retrospective analyses [8,9,10,11,12,13]

Methods

Results

Conclusion