In advanced breast cancer, physicians should have available (in addition to ER, PR, Ki-67 and HER2) the results for BRCA and PI3K in HR-positive, HER2-negative cases, ESR1 in ER-positive, HER2-negative cases after progression of first-line hormonal therapy including a CDK inhibitor, and PD-L1 in TNBC. The gene discussed is ESR1; the disease is breast cancer.