The classification of BC is based on the expression of estrogen receptors (ERs) and progesterone receptors (PRs), the HER2 status, and the Ki-67 levels, resulting in subtypes such as luminal A, luminal B, HER2-positive, and basal-like, with triple-negative BC being the most prevalent within the basal-like group [2]. Here, ESR1 is linked to breast cancer.