An update on gastroenteropancreatic neuroendocrine tumors.

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are a heterogeneous group of neoplasms arising from the diffuse neuroendocrine system. The incidence of GEP-NETs has increased markedly over the past 3 decades, probably as a result of trends in imaging and improvements in diagnosis. Advances in molecular biology have translated into an expansion of treatment options for patients with GEP-NETs. Somatostatin analogs, initially developed for control of hormonal syndromes, have recently been proven to inhibit tumor growth. Newer drugs, targeting angiogenesis and mammalian target of rapamycin (mTOR) pathways, have been approved for progressive pancreatic NETs; however, their role in nonpancreatic NETs remains controversial. Alkylating cytotoxic agents, such as streptozocin and temozolomide, play an important role in the treatment of pancreatic NETs, although estimated response rates vary widely and phase III data are lacking. During the next few years, randomized clinical trials are expected to provide more clarity regarding the role of radiolabeled somatostatin analogs. Predictive biomarkers that would allow for individualized selection of treatments are needed.