Retrospective cohort study of de-escalated adjuvant therapy for early breast cancer in younger patients with low genomic risk

It is not clear whether omission of adjuvant radiotherapy (RT) or endocrine therapy (ET) is associated with higher locoregional recurrence (LRR) rates among patients with early-stage breast cancer and low genomic risk. In a cohort study of 2249 patients aged 50 to 69 years with early-stage, HR-positive breast cancer and Oncotype DX score of 18 or below, patients receiving RT had the lowest 72-month LRR regardless of ET duration, followed by patients receiving ET alone. Patients who did not complete any adjuvant therapy had the highest LRR. ODX RS might be a valuable tool for selecting candidates for RT omission among patients willing to accept a low absolute but slightly higher relative risk of LRR with de-escalated therapy.