In 2017, a 61-year-old female patient presented with a Luminal B lobular-invasive carcinoma G2 of the breast (pT1c, pN1a (1/2 sn), M0, R0, L0, V0, Pn0), ER (estrogen receptor) 100%, PgR (progesterone receptor) 0%, HER2 0, Ki-67 10%. The gene discussed is ESR1; the disease is invasive carcinoma.