ESR1 and cancer: Breast cancer (BC) is one of the most serious threats to women's health in China, and is the most common causes of cancer death of women in the world.[1] The negative immunohistochemical detection results of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor-2 (Her-2) are defined as triple-negative breast cancer (TNBC).[2] Compared with other types of BC, TNBC has a high risk of invasion, local recurrence, and metastasis.