Neuroendocrine Tumors of the Pancreas

Pancreatic neuroendocrine tumors (PNETs) comprise a diverse, heterogeneous group of tumours that range in presentation and biologic behavior, including small, asymptomatic, incidentally discovered, nonfunctional neoplasms, functional tumors (both localizable and unlocalizable) with associated clinical syndromes, and diffuse metastatic disease. Based on its functional status, the malignancy of a PNET can vary, from the benign (insulinoma) to that which is commonly malignant more than 50% of the time (gastrinoma, somatostatinoma). According to a recent study, PNETs appear to be increasing in incidence or at least in clinical detection; currently the disorder accounts for 1 to 2% of pancreatic tumors and with a reported clinical incidence of one to five cases per million persons annually in the United States. Nonfunctional PNETs make up the majority of cases, and comprise 2% of all pancreatic malignancies. Treatment has been primarily done through surgical management, particularly via resection. However, medical management has played a more increased role for patients where the disease is advanced, encompassing biotherapy, chemotherapy, and targeted therapies such as peptide receptor radionuclide therapy (PRRT). For nonfunctional PNETs—insulinomas, gastrinomas, glucagonomas, somatostatinomas, and VIPomas—the epidemiology, biology of disease, clinical presentation and diagnosis, localization of tumor, operative management considerations, surgical management of primary tumor, and prognosis and outcomes of each are discussed. This review contains 6 figures, 18 tables, and 58 references Keywords: Pancreas, neuroendocrine tumor, gastrinoma, somatostatinoma, VIPoma, insulinoma, incidentaloma, glucagonoma, enucleation