Neuroendocrine tumors of the gastro-entero-pancreatic system.

Gastro-entero-pancreatic (GEP) neuroendocrine tumors (NETs) are rare neoplasms, although their prevalence has increased substantially over the past three decades. Moreover, there has been an increased clinical recognition and characterization of these neoplasms. They show extremely variable biological behavior and clinical course. Most NETs have endocrine function and secrete peptides and neuroamines that cause distinct clinical syndromes, including carcinoid syndrome; however, many are clinically silent until late presentation with mass effects. Investigation and management should be individualized for each patient, taking into account the likely natural history of the tumor and general health of the patient. Management strategies include surgery for cure or palliation, and a variety of other cytoreductive techniques, and medical treatment including chemotherapy, and biotherapy to control symptoms due to hormone release and tumor growth, with somatostatin analogues (SSAs) and alpha-interferon. New biological agents and somatostatin-tagged radionuclides are under investigation. Advances in the therapy and development of centers of excellence which coordinate multicenter studies, are needed to improve diagnosis, treatment and therefore survival of patients with GEP NETs.