Firstly, novel and efficacious approaches, including aromatase inhibitor, fulvestrant and CDK4/6 inhibitor ER/PR positive patients, trastuzumab, pertuzumab and trastuzumab emtansine for HER2 positive patients, platinum, PD1/PDL1 inhibitor and PARP inhibitor for ER/PR/HER2 negative patients, have greatly enriched the comprehensive treatment of breast cancer, and improved the prognosis of breast cancer patients.27, 28 The intrinsic characteristics of breast cancer are being changed by the above therapeutic approaches. This evidence concerns the gene ESR1 and breast cancer.