It is well known that different combinations of estrogen receptor (ER), progesterone receptor (PgR), human epidermal growth factor receptor 2 (Her2) status [20] and tumor grade define at least four molecular subtypes of breast cancer, luminal A, luminal B, Her2-enriched (Her2+), and basal/triple-negative [21]. The gene discussed is ESR1; the disease is neoplasm.