The subgroup analyses based on menopausal status suggested that EP is prognostic in ER+/HER2− BC patients in the premenopausal patients (HR = 6.7, 95% CI = 2.4 to 18.3; P < 0.0001) and postmenopausal patients (HR = 3.3, 95% CI = 1.3 to 8.5; P = 0.0069) (Figure 3A). Here, ESR1 is linked to breast cancer.