ESR1 and breast cancer: The frequency of HER2/neu positive (3+) breast carcinoma, triple negative breast cancers, Luminal A (ER+, PR+, HER2/neu−, Ki67 < 14%) breast cancers, and Luminal B (ER+, PR+, HER2/neu−, Ki67 > 14%) breast carcinomas were calculated, and the results are shown in Table 1.