During the univariate analysis of breast cancer subtypes (Table 4), we noticed that BRmet50 could be used to segregate ER-positive (luminal tumors) and intermediate grade tumors regardless of tumor size and lymph-node status into good and poor prognostic subcategories (hazard ratio for a poor prognosis: 2.5; p<0.001) but not for those with ER-negative status or those with high-grade (Table 4). Here, ESR1 is linked to breast cancer.