Triple-negative breast cancer (TNBC) accounts for 10–20.8% of all pathological types of BC (Li et al., 2017) and is described as BC with no expression of estrogen receptors (ERs), progesterone receptors (PRs), and human epidermal growth factor receptor-2 (HER-2) on immunohistochemical examination of cancer tissues. The gene discussed is ESR1; the disease is breast cancer.