ESR1 and invasive carcinoma: In total, the 635 cases of invasive carcinoma were classified into 5 clinical subtypes using immunohistochemical markers as follows: Luminal A (ER+ and/or PgR+ and HER2−), luminal B (ER+ and/or PgR+ and HER2+), HER2+/ER− (ER−, PgR− and HER+), basal-like (ER−, PgR−, HER2−, CK 5/6+ and/or HER1+) and unclassified (negative for all 5 markers) (24).