The resistance to endocrine therapy is likely an important contributor to the racial disparity in breast cancer mortality because it is clear that Black women with ER+/PR + tumors have higher mortality [6] as well as breast cancer recurrence [7], compared to White women with ER+/PR + tumors, and the difference is not observed among Black and White women with ER−/PR− tumors. Here, ESR1 is linked to breast cancer.