Others categorizations could have been considered and, in particular, ER+ BC can also be dichotomized into luminal A (ER+/HER2- breast tumor, with low grade and low proliferation) and luminal B (which regroups high proliferative ER+/HER2- breast carcinoma and some ER+/HER2+ tumors). This evidence concerns the gene ESR1 and breast carcinoma.