AUTHOR=Liu Jing , Huang Suning , Bi Zhuofei , Zhang Xiaoxue , He Ziqing , Lan Xiaowen , Tan Yuting , Lin Xiao , Zhou Wenyi , Huang Xiaobo 

TITLE=De-escalated radiotherapy for HER2-overexpressing breast cancer patients with 1-3 positive lymph nodes undergoing anti-HER2 targeted therapy

JOURNAL=Frontiers in Oncology

VOLUME=13

YEAR=2023

URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2023.1280900

DOI=10.3389/fonc.2023.1280900

ISSN=2234-943X

ABSTRACT=<sec><title>Background</title><p>In the era of anti-HER2 targeted therapy, the potential clinical feasibility of considering HER2-overexpressing breast cancer cases presenting with 1-3 positive axillary lymph nodes as low-risk, and thereby contemplating postoperative radiotherapy reduction, remains an important subject for in-depth examination. The aim of this retrospective study was to evaluate the effectiveness of de-escalated radiotherapy in T1-2N1M0 HER2-overexpressing breast cancer patients receiving anti-HER2 targeted therapy. Specifically, omitting regional lymph node irradiation (RNI) after breast-conserving surgery and only performing whole-breast irradiation or omitting postmastectomy radiation therapy.</p></sec><sec><title>Methods</title><p>A retrospective analysis was conducted on 429 patients with stage T1-2N1M0 primary invasive HER2-overexpressing breast cancer from our center between 2004 and 2018. Patients who received anti-HER2 targeted therapy were divided into an RNI group and a no RNI group to assess the role of RNI. The prognostic role of RNI was investigated via the Kaplan-Meier method and Cox proportional hazards modeling.</p></sec><sec><title>Results</title><p>The median follow-up time was 46.8 months (range 7.1–225.8 months). In the anti-HER2 targeted therapy group RNI yielded no significant improvements in invasive disease-free survival (IDFS) (<italic>p</italic> = 0.940), local-regional recurrence-free survival (<italic>p</italic> = 0.380), distant metastases-free survival (<italic>p</italic> = 0.698), or overall survival (<italic>p</italic> = 0.403). Estrogen receptor (ER) status (hazard ratio [HR] 0.105, 95% confidence interval [CI] 0.023–0.749, <italic>p</italic> = 0.004) and lymph vascular invasion status (LVI) (HR 5.721, 95% CI 1.586–20.633, <italic>p</italic> = 0.008) were identified as independent prognostic factors for IDFS, and ER-positive and LVI-negative patients exhibited better prognoses.</p></sec><sec><title>Conclusion</title><p>Omitting RNI may be a safe option in T1-2N1 HER2-overexpressing breast cancer patients receiving standardized anti-HER2 targeted therapy; particularly in ER-positive or LVI-negative subgroups.</p></sec>