Owing to the high degree of heterogeneity at the molecular level, the three distinct subtypes of BC, namely Luminal (positive for ER and/or PR), Her‐2 overexpression (negative for ER and PR, positive for Her‐2), and TNBC (lack of ER, PR, and Her‐2 expression), have different biological, molecular, and clinical characteristics.28, 29. Here, ESR1 is linked to breast cancer.