ESR1 and breast cancer: In this multi-institutional study, we assessed TMEM doorway score, as well as macrophage and microvascular density in treatment-naïve breast tissues taken from a large group of patients (418 total, with 184 Black, 146 White, and 88 of other racial backgrounds) with the goal of providing insight into whether baseline differences in these pro-metastatic markers exist and are associated with Black vs White racial disparities in breast cancer outcomes, particularly in ER + /HER2- breast cancer.