ESR1 and neoplasm: Currently, Oncotype DX® (21 genes) and MammaPrint® (70 genes) help clinicians to make decision on the kind of treatment in two specific clinical settings: adjuvant chemotherapy in patients with early ER+/HER2− tumor and adjuvant extended hormone therapy in post-menopausal patients with ER+ tumor, thus helping to de-escalate systemic therapy.