To date, four major invasive breast carcinoma genetic subtypes have been identified with prognostic and therapeutic relevance, such as the luminal subtype A, presenting high expression of estrogen (ERs) and progesterone (PRs) receptors without human growth factor receptor type 2 (Her2) overexpression and low cell proliferation index; the luminal subtype B (ER PR+ and high proliferation index); a group of tumors overexpressing Her2 (ER−/PR− and Her2+), and finally the triple negative subgroup or TNBC (ER/PR− and Her2−) [2,3]. The gene discussed is ESR1; the disease is invasive breast carcinoma.