Practical Model to Optimize the Strategy of Adjuvant Postmastectomy Radiotherapy in T1-2N1 Breast Cancer With Modern Systemic Therapy

Abstract

PurposeThe effect of adjuvant irradiation after mastectomy in early-stage breast cancer patients remains controversial. The present study aims to explore the clinical benefit obtained from adjuvant radiotherapy among post-mastectomy pT1-2N1 breast cancer patients who received adjuvant modern systemic therapy.MethodsMedical records of consecutive patients with pT1-2N1 breast cancer who received mastectomy in our institution between January 2009 and December 2016 were retrospectively reviewed. High-risk features consist of patient age, number of positive lymph nodes, T stage, and Ki67 index, which were developed previously at our institution using early-stage breast cancer patients after mastectomy without adjuvant radiotherapy. Differences of survival and local recurrence were compared between no-postmastectomy radiotherapy (PMRT) and PMRT group according to number of risk factors. The time-to-event curves were calculated by the Kaplan–Meier methods and compared by the log-rank test. Propensity score matching (PSM) was performed to reduce the imbalances in patient characteristics.ResultsA total of 548 patients were enrolled (no-PMRT: 259 and PMRT: 289). After a median follow-up of 69 months, the 5-year rate of DFS, BCSS, and LRR in the overall cohort was 90.2%, 97.4%, and 3.6%, respectively. PMRT did not significantly improve DFS, BCSS, and LRRFS in the whole cohort. Patients were divided into low-risk (with no or one risk factor) and high-risk (with two or more risk factors) groups. According to the univariable and multivariable analysis, high-risk group (HR = 1.81, 95% CI 1.11–2.98, p = 0.02) was demonstrated as an independent risk factor for DFS. For the high-risk group, PMRT significantly improved DFS from 81.4% to 91.9% and BCSS from 95.5% to 98.6% and decreased the 5-year rate of LRR from 5.6% to 1.4%, respectively (p < 0.01, p = 0.05, and p = 0.06). However, no survival benefit from PMRT was observed in the low-risk group in terms of DFS, BCSS, and LRR (p = 0.45, p = 0.51, and p = 0.99, respectively). In multivariate analysis, PMRT remained an independent prognostic factor for DFS (HR = 0.50, 95% CI 0.24–1.00, p = 0.05) in the high-risk group. After PSM analysis, the survival benefit of PMRT was sustained in high-risk patients.ConclusionPMRT significantly improved DFS in high-risk pT1-2N1 breast cancer patients, but not in low-risk patients. Independent validation of our scoring system is recommended.

The optimal regional irradiation volume for breast cancer patients: A comprehensive systematic review and network meta-analysis of published studies

“…Therefore, one size did not fit all, and not all BCs could benefit from comprehensive RNI. Based on our established clinical risk model for N1 breast cancer ( 45 , 46 ), our group initiated a prospective randomized clinical trial to investigate whether a part of pN1 breast cancer patients could be safely omitted from IMNI by using a clinical-genomic model, and the trial was under recruiting(NCT04517266). The preliminary results of enrolled 75 patients showed that among clinically high-risk pN1 BC, which is defined as having at least two of the five clinical risk factors (age≤40, three positive LN(lymph node), T2 stage, grade 3, and Ki-67 index≥14%), 70% of them present with genomic high risk, and 30% present with genomic low risk, and whether those clinical high-risk but genomic low-risk BC patients could be omitted from IMNI still needs long-term follow-up of our research ( 47 ).…”

The prognostic differences and the effect of postmastectomy radiotherapy between post‐chemotherapy ypT1‐2ypN1 and de novo pT1‐2N1 breast cancer

“…The role of PMRT in whole pT1‐2N1M0 BC patients and the heterogenous impact of PMRT in patient subsets remain controversial. 24 Previous studies demonstrated that PMRT had no effect on prognosis in pT1‐2N1M0 BC patients, 25 , 26 but other studies concluded that PMRT was valuable. 27 , 28 , 29 The EBCTCG meta‐analysis clarified the benefit of PMRT in node‐positive BC patients and confirmed that radiotherapy reduced locoregional recurrence, overall recurrence and BC mortality in 1314 patients with 1–3 positive nodes.…”

Radiation Therapy for Breast Cancer pT1–3N0–1M0 after Mastectomy or Subcutaneous/Skin-Preserving Mastectomy with Reconstruction. Literature Review

“…В китайском исследовании 2022 г. за 7-летний период наблюдения изучена группа пациенток РМЖ pT 1-2 N 1 (n=548), которым выполнена мастэктомия [13]. Признаки высокого риска рецидива включают в себя возраст пациентки, количество положительных лимфатических узлов, Т-стадию и индекс Ki67.…”

“…Таким образом, ЛТ значительно улучшила безрецидивную выживаемость у пациентов РМЖ pT 1-2 N 1 с высоким риском, но не у пациентов с низким риском [13].…”