Moreover, other histological data were collected: histotype (including ductal carcinoma (IDC) and invasive lobular carcinoma (ILC)), grading (divided into G1, G2, or G3), and tumor class, which includes the hormone receptor status and the proliferation index percentage (Luminal A: ER+, HER2− and low ki67; Luminal B: ER+, HER2 −/+ and high ki67; HER2 overexpressed; Triple Negative (TN): ER−, PgR−, HER2−). The gene discussed is ESR1; the disease is invasive lobular breast carcinoma.