Top Line: What are the long term outcomes of response adapted radiation for node positive breast cancer following neoadjuvant systemic therapy?
The Study: The 5 year results of NSABP B-51 showed that regional nodal irradiation did not significantly improve outcomes in patients with node positive breast cancer who had a pathologic complete response to systemic therapy. RAPCHEM was another prospective registry trial that investigated a response adapted approach to adjuvant RT for breast cancer, and here we have 10 year outcomes. The trial enrolled 838 patients with cT1-2N1 breast cancer with no more than 3 suspicious nodes on imaging. All received initial systemic therapy followed by surgery. Low risk patients (35%) had pathologic complete response in the nodes (ypN0) and they received whole breast RT or no RT if they had mastectomy. Intermediate risk patients (ypN1, 44%) received adjuvant RT to the breast or chest wall and levels I-II of the axilla (but not III or IV). High risk patients (ypN2-3) received breast or chest wall RT and comprehensive nodal irradiation. At 10 years, the overall rate of isolated LRR was 2.9% (2.4% LR, 3.2% IR, 2.8% HR), which was only marginally higher than the 5 year LRR rate of 2.2% suggesting few additional late recurrences. Notable findings were a higher risk of LRR among hormone receptor negative patients, which tended to be in the first 5 years, and that nonadherence to RT recommendations among high risk patients led to a higher risk of LRR. Importantly, this was a prospective registry study, not a randomized trial, and adherence to treatment guidelines was 64%.
TBL: Long term outcomes of RAPCHEM support the safety of tailoring adjuvant RT for breast cancer based on response to systemic therapy. | Mauritz, Lancet Oncol 2026
The Study: The 5 year results of NSABP B-51 showed that regional nodal irradiation did not significantly improve outcomes in patients with node positive breast cancer who had a pathologic complete response to systemic therapy. RAPCHEM was another prospective registry trial that investigated a response adapted approach to adjuvant RT for breast cancer, and here we have 10 year outcomes. The trial enrolled 838 patients with cT1-2N1 breast cancer with no more than 3 suspicious nodes on imaging. All received initial systemic therapy followed by surgery. Low risk patients (35%) had pathologic complete response in the nodes (ypN0) and they received whole breast RT or no RT if they had mastectomy. Intermediate risk patients (ypN1, 44%) received adjuvant RT to the breast or chest wall and levels I-II of the axilla (but not III or IV). High risk patients (ypN2-3) received breast or chest wall RT and comprehensive nodal irradiation. At 10 years, the overall rate of isolated LRR was 2.9% (2.4% LR, 3.2% IR, 2.8% HR), which was only marginally higher than the 5 year LRR rate of 2.2% suggesting few additional late recurrences. Notable findings were a higher risk of LRR among hormone receptor negative patients, which tended to be in the first 5 years, and that nonadherence to RT recommendations among high risk patients led to a higher risk of LRR. Importantly, this was a prospective registry study, not a randomized trial, and adherence to treatment guidelines was 64%.
TBL: Long term outcomes of RAPCHEM support the safety of tailoring adjuvant RT for breast cancer based on response to systemic therapy. | Mauritz, Lancet Oncol 2026