ESR1 and triple-negative breast carcinoma: Basal-like and claudin-low subtypes, characterized by the lack of estrogen receptor (ER), progesterone receptor (PR), and HER2 expression, belong to the type of triple-negative breast cancer (TNBC) and have a greater possibility of distant disease recurrence and a high frequency of visceral metastases (Kast et al., 2015).