ESR1 and breast carcinoma: And while reference to ER+ (i.e., ERα+/PR−) breast cancer will still be appropriate, designation of specific double (i.e., ERα/ERβ-variant, ERα/AR, and ERβ-variant/AR) or triple (i.e., ERα, ERβ-variant, and AR) hormone receptor-positive tumors may have greater clinical significance.