ESR1 and breast cancer: In the unadjusted model, the following factors were associated with a shorter time to BM diagnosis: post-menopausal state at initial breast cancer diagnosis (HR = 1.49; 95% CI:1.02–2.21, p = 0.04), other ethnicities (Hispanic or Arabic) (HR = 1.49; 95% CI 1.02–2.21, p = 0.04), HER2+ status (HR=2.19; 95% CI 1.26–3.82, p = 0.01), and ER-/HER2+ (HR = 2.21; 95% CI 1.22–4.01, p = 0.01) and ER+/HER2+ (HR=2.14; 95% CI 1.25–3.65, p = 0.01) subtypes.