Impact of clinical-pathological factors on locoregional recurrence in mastectomy patients with T1-2N1 breast cancer: who can omit adjuvant radiotherapy?

Xiaofang Wang,Jinli Ma,Li Zhang,Xiaoli Yu,Zhen Zhang,Xiaomao Guo,Jurui Luo,Xingxing Chen,Zhimin Shao,Xiaomeng Zhang,Zhaozhi Yang,Xin Mei,Xuanyi Wang

doi:10.1007/s10549-021-06378-2

Abstract

PurposePostmastectomy radiation therapy (PMRT) in T1–T2 tumors with 1–3 positive axillary lymph nodes (ALNs) is controversial. This study was to identify prognostic factors of locoregional control (LRC) following mastectomy with or without PMRT for patients with T1-2N1 breast cancer and to discuss the selection of patients who might omit PMRT.Materials and methodsBetween January 2006 and December 2012, the data of 1474 postmastectomy patients staged pT1-2N1 were analyzed. PMRT was applied in 663 patients. LRC and disease-free survival (DFS) were calculated using the Kaplan–Meier method. Cox regression model was applied in the univariate and multivariate analyses to recognize the recurrence risk factors.ResultsWith the median follow-up duration of 93 months (range, 5–168 months), 78 patients (5.3%) failed to secure LRC and 220 patients (14.9%) experienced any recurrence. The 7.7-year LRC and DFS was 94.9% and 85.4% respectively in the entire cohort. PMRT significantly improved 7.7-year LRC from 93.4% to 96.6% (p = 0.005), but not the DFS (p = 0.335). Multivariate analysis revealed that PMRT was an independent prognostic factor of LRC (p < 0.001), meanwhile, age ≤ 40 years (p = 0.012), histological grade 3 (p = 0.004), 2–3 positive nodes (p < 0.001) and tumor size of 3–5 cm (p = 0.045) were significantly associated with decreased LRC. The 7.7-year LRC for patients with 0, 1, and 2–4 risk factors was 97.7% / 98.9% (p = 0.233), 95.3% / 98.0% (p = 0.092), and 80.3% / 94.8% (p < 0.001) in the non-PMRT and PMRT group, respectively.ConclusionsIn patients with T1-2N1 breast cancer, clinical-pathological factors including young age, histological grade 3, 2–3 positive nodes, and tumor size of 3–5 cm were identified to be predictors of a poorer LRC following mastectomy. Patients with 0–1 risk factor might consider the omission of PMRT.

Highlights

Postmastectomy radiotherapy (PMRT) has long been the standard for patients with tumors larger than 5 cm or with 4 or more positive axillary lymph nodes (ALNs)
When conducting competing risk analysis in consideration of death, the main competing event in the study, we demonstrated that the benefit from PMRT was retained in improving locoregional control (LRC) (p = 0.003)
Our study offers LRC and disease-free survival (DFS) estimates and makes PMRT recommendations according to risk stratification in the era of modern medicine

Summary

Introduction

Postmastectomy radiotherapy (PMRT) has long been the standard for patients with tumors larger than 5 cm or with 4 or more positive axillary lymph nodes (ALNs). For early staged patients with T1–2 tumors and 1–3 positive ALNs, the role of PMRT remains controversial. The NCCN guideline strongly recommends the locoregional irradiation in patients staged pT1-2N1 in recent years [3]. Some concerns were evoked from today’s perspective: patients who participated were not all staged at pT1-2N1; novel systemic treatment was not available at the time of some trials conducted; in terms of toxicity, the application of novel radiation techniques is expected to further reduce radiation-associated heart disease. As proposed by ASTRO and St. Gallen Consensus [4, 5], PMRT should be conducted individually in consideration of risk factors and toxicity in the early staged patients

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