Patients with estrogen receptor (ER)-positive, HER2-negative early breast cancer with tumors that have a low risk-of-recurrence (ROR) score on the Prosigna 50-gene test were able to safely avoid adjuvant chemotherapy, according to results of the phase 3 OPTIMA trial presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting (Abstract 500). “We have shown that patients with low ROR score tumors gain minimum, if any, chemotherapy benefit,” said study presenter Robert C.