Management of gastroentero-pancreatic neuroendocrine tumors (GEP-NETs)

Neuroendocrine tumors (NETs) are relatively rare neoplasms that often present as diagnostic dilemmas due to obscure or non-specific symptoms. The ability of carcinoid tumors to cause clinical symptoms by secretion of hormones or biogenic amines is best recognised in the form of the carcinoid syndrome. Although generally slow growing, a significant minority demonstrate aggressive tumor growth. Ten-twenty percent of pancreatic NETs may be associated with hereditary disorders such as multiple endocrine neoplasia-1 (MEN-1) and less frequently, Von Hippel Lindau, which should be considered in the investigation and management of these patients. A small percentage of NETs are associated with co-existing synchronous non-carcinoid neoplasm. The aim of this paper was to review the optimal management in patients with NETs. The therapeutic options which are reviewed, including the use of somatostatin analogues, the role of surgery, the use of chemotherapy, biotherapy using interferon, peptide receptor targeted therapy. In addition, the challenging interventional management of liver metastases is discussed, including the role of hepatic-artery embolization, radiofrequency ablation and the place of orthotoptic liver transplantation in selected patients. Authors have focused on the newest therapeutic modalities, e.g., radionuclide peptide receptor targeted therapy with Yttrium-90 and Lutetium-177, the newest somatostatin analogues such as pasireotide and angiogenic inhibitors. In conclusion, with the increasing number of investigative procedures and therapeutic options available to diagnose and treat carcinoid tumors, it is vital to have a multidisciplinary approach. Furthermore, additional scientific research and controlled clinical trials are needed to determine the efficacy of the many treatment options, which for these rare tumors can only be achieved by collaboration.