ESR1 and breast cancer: Based on the efficacy and safety data discussed, it is recommended to offer adjuvant chemotherapy for fit older breast cancer patients with node-positive (N+) ER-negative disease and to consider chemotherapy for patients with node-negative (N0) ER-negative disease, as well as for patients with ER-positive disease, if additional unfavorable features (high tumor burden i.e., ≥4 positive nodes, high risk on genetic-based assay or classical biological features) are present [41].