Study Finds Regional Nodal Irradiation Does Not Lower Invasive Breast Cancer Recurrence Rates

Recent findings from the NRG-NSABP B-51/RTOG 1304 clinical trial revealed that adding regional nodal irradiation (RNI) does not significantly reduce the risk of invasive breast cancer recurrence in patients who initially presented with positive axillary lymph nodes that later converted to negative following neoadjuvant chemotherapy. The study included 1,641 participants undergoing either mastectomy or lumpectomy, with profiles stratified by hormone receptor status, HER2 status, adjuvant therapies, and response to treatment. Patients with HER2-positive tumors received dual HER2-targeted therapy, while hormone-sensitive cases were given endocrine therapy. The primary measure was the invasive breast cancer recurrence-free interval (IBCRFI). Although the trial was ongoing, initial analysis after 109 IBCRFI events showed no significant benefit of RNI; the five-year recurrence rates were similar between groups (approximately 92%). This outcome emphasizes that pathological complete response (pCR) in axillary nodes predicts a lack of benefit from RNI in this context, challenging previous assumptions about the universal benefit of regional irradiation. Lead author Dr. Eleftherios Mamounas stated that they will continue to monitor long-term outcomes. The findings contribute critical insights into personalized treatment approaches in breast cancer, highlighting that not all patients with initial node positivity will benefit from additional regional radiation therapy. Source: https://medicalxpress.com/news/2025-06-addition-regional-nodal-irradiation-decrease.html