ESR1 and breast carcinoma: The breast cancer subtype was luminal A type (ER + , HER2 -, Ki67 < 15%) in 19 (32%), luminal B type (ER + , HER2-, Ki67 > 15%) in 23 (39%), luminal HER2 type in 4 (7%), HER2-enriched type in 4 (7%) and TN type in 9 (15%) cases (Table 1).