ESR1 and triple-negative breast carcinoma: MBC is characterized by strong invasiveness, poor prognosis, and is often negative in estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) tests; its prognosis is worse than that of triple-negative breast cancer, and the survival rate is lower (Bae et al., 2011; El Zein et al., 2017).