AUTHOR=Sun Guang-Yi , Wen Ge , Zhang Yu-Jing , Tang Yu , Jing Hao , Fang Hui , Wang Jian-Yang , Zhang Jiang-Hu , Zhao Xu-Ran , Chen Si-Ye , Song Yong-Wen , Jin Jing , Liu Yue-Ping , Tang Yuan , Qi Shu-Nan , Li Ning , Chen Bo , Lu Ning-Ning , Li Ye-Xiong , Wang Shu-Lian 

TITLE=Risk factors to identify the indication for regional nodal irradiation in T1-2N1M0 breast cancer: A joint analysis of 4,243 real-world cases from two institutions

JOURNAL=Frontiers in Oncology

VOLUME=12

YEAR=2022

URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2022.955381

DOI=10.3389/fonc.2022.955381

ISSN=2234-943X

ABSTRACT=<sec><title>Purpose</title><p>The aim of this study is to evaluate the role of regional nodal irradiation (RNI) in patients with T1-2N1M0 breast cancer and to identify the subgroup that could benefit from RNI.</p></sec><sec><title>Methods and materials</title><p>A total of 4,243 women with pT1-2N1M0 breast cancer treated at two institutions in China were retrospectively reviewed. Survival rates were calculated by the Kaplan–Meier method and compared by the log-rank test. The association of risk factors with survival outcomes was evaluated using multivariable proportional hazards regression.</p></sec><sec><title>Results</title><p>A total of 932 patients (22.0%) received RNI. At a median follow-up of 5.9 years, the 5-year locoregional recurrence (LRR), distant metastasis (DM), disease-free survival (DFS), and overall survival (OS) rates were 4.0% and 7.2% (<italic>P</italic> = 0.001), 13.2% and 10.6% (<italic>P</italic> = 0.465), 85.0% and 84.7% (<italic>P</italic> = 0.131), and 93.9% and 92.8% (<italic>P</italic> = 0.004) in the RNI and non-RNI groups, respectively. Multivariate analysis revealed that RNI was an independent prognostic factor for lower LRR (<italic>P</italic> = 0.001) and longer DFS (<italic>P</italic> = 0.013). Patients were stratified into low-, intermediate-, and high-risk groups based on the eight non-therapeutic risk factors. RNI significantly decreased the 5-year LRR (2.2% vs. 7.0%, <italic>P</italic> = 0.001) and improved the 5-year DFS (88.8% vs. 84.9%, <italic>P</italic> = 0.015) and OS (95.8% vs. 93.9%, <italic>P</italic> = 0.010) in the intermediate-risk group. However, neither the low-risk group nor the high-risk group had survival benefit from RNI.</p></sec><sec><title>Conclusion</title><p>T1-2N1M0 breast cancer is a heterogeneous disease. We found that RNI only improved survival in the intermediate-risk group. It might be omitted in low-risk patients, and the role of RNI in high-risk patients needs further study.</p></sec>