Radiotherapy use and incidence of locoregional recurrence in favorable-risk, node-positive breast cancer

Little is known about rates of locoregional recurrence (LRR) with and without regional nodal irradiation (RNI) in breast cancer patients with limited nodal disease and favorable biology. A secondary analysis of the SWOG S1007 trial (patients with HR-positive, HER2-negative disease with 1 to 3 nodes involved, and a Oncotype recurrence score 25 or less) found a cumulative incidence of LRR between 1 and 5 years of 0.85% among patients who underwent breast-conserving surgery and radiotherapy with RNI; 0.55% after breast-conserving surgery with radiotherapy without RNI; 0.11% after mastectomy with postmastectomy radiotherapy; and 1,7% after mastectomy without radiotherapy. The authors conclude that LRR rates were low in patients who did not receive RNI, suggesting a questionable role of RNI in this population.