Nonfunctional Pancreatic Neuroendocrine Tumors: Advances in Diagnosis, Management, and Controversies

In this article, we aimed to review the literature on the clinics and management of nonfunctional pancreatic neuroendocrine tumors (NPNET). Pancreatic neuroendocrine tumors (PNET) are rare tumors with a <1/100,000 incidence and constitute approximately 2 to 10% of all pancreatic tumors. Nonfunctional PNETs are difficult to detect at early stages since they have no symptoms. Except those detected accidentally during different diagnoses, the majority of PNETs are detected in the advanced stages, with symptoms related to tumor size or liver metastasis. We reviewed the studies published in the English medical literature through PubMed and summarized the clinical features and current approaches to the treatment and follow-up of the NPNET. The common imaging techniques used for the detection of tumor localization, size, locoregional, and metastatic involvement are contrasted computed tomography, magnetic resonance imaging, endoscopic ultrasonography, and somatostatin receptor scintigraphy. Surgical resection is the only curative treatment. However, in advanced locoregional disease and liver metastasis, interventive ablative therapies such as palliative reductive surgery, selective hepatic arterial embolization, radiofrequency ablation; and systemic therapies, such as peptide receptor radionuclide therapy, chemotherapy, somatostatin analogous therapy, interferon, VEGF inhibitor, and mTOR inhibitor may be used as symptom relieving or may improve progression-free survival and total survival. Current knowledge on NPNET shows that the treatment should be personalized considering the prognostic features and life expectancy of the patient.