Therapeutic decisions on BC are based on its three main subtypes, luminal (A and B), which express the hormone receptor such as estrogen receptor or progesterone receptor); human epidermal growth factor receptor 2-positive; and triple-negative, which lacks the expressions of all three receptors (estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2) [10]. Here, ESR1 is linked to breast cancer.