Characterized by the lack of expression of estrogen receptor (ER-), progesterone receptor (PR-), and human epidermal growth factor receptor-2 (HER2-) [16], triple-negative breast cancer (TNBC) is the most aggressive one, and unfortunately, chemotherapy represents the only treatment against TNBC [15,16,17]. This evidence concerns the gene ESR1 and triple-negative breast carcinoma.