Among all the breast cancers, triple-negative breast cancer (TNBC), with the absence of targeted therapy, is a more heterogeneous subtype of breast cancer immunohistochemically defined by lack of the expression of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER2) [2,3]. The gene discussed is ESR1; the disease is breast carcinoma.