In normal epithelial breast cells, neurotensin is expressed and upregulated by estrogens; the peptide is also expressed in the ductal and invasive components of invasive ductal breast carcinomas, and a high neurotensin receptor 1 expression has been related to tumor size, number of metastatic lymph nodes, and SBR (Scarff–Bloom–Richardson) grade [222]. The gene discussed is NTSR1; the disease is neoplasm.