ESR1 and breast cancer: The patient initially received a diagnosis of stage IIIA left breast cancer, with a clinical stage of T3 (tumor is more than 5 cm across), clinical stage N2a (clinically fixed or matted axillary lymph nodes), with weakly positive estrogen receptor and progesterone receptor (ER/PR) and human epidermal growth factor receptor 2 (HER2) positive left breast invasive ductal carcinoma in September 2022 [4].