Specifically, for the triple-negative breast cancer (TNBC) subtype, which lacks specific receptors, including estrogen receptor (ER)-, progesterone receptor (PR)-, and human epidermal growth factor receptor-2 (HER2)-), chemotherapy is particularly suggested due to its aggressive nature and lack of targeted therapeutic avenues [82,134]. The gene discussed is ESR1; the disease is triple-negative breast carcinoma.