ESR1 and breast cancer: In patients (per-protocol population) with low clinical risk and high risk by the 70-gene signature, no significant chemotherapy benefit was observed.30 In contrast to the MINDACT findings, our results (consistent with the prospective-retrospective RS validation studies showing minimal chemotherapy benefit in low RS patients15) strongly support forgoing chemotherapy in patients with ER+ HER2-negative breast cancer with micrometastases/1–3 positive nodes and RS < 18 and treating them with endocrine therapy alone.