Recent studies have compared the prognostic significance of three-(ER, PgR, HER2) and five-biomarker (ER, PgR, HER2, CK5/6, EGFR) surrogate panels to define intrinsic breast cancer subtypes and have suggested that the extended immunopanel provided more specific definition of basal like breast cancer, which can better predict survival of breast cancer patients [25]. Here, ESR1 is linked to breast cancer.