Endoscopic imaging in the management of gastroenteropancreatic neuroendocrine tumors

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are a heterogeneous group of tumors deriving from the gastrointestinal (GI) neuroendocrine system. Since these neoplasms are usually very small, located deeply within the retroperitoneum or into an extramucosal site of the GI tract and, lastly, because they may be multi-sited, radiological imaging modalities, in combination with endoscopy, are the diagnostic workhorses in patients with GEP-NETs. Endoscopic approach is useful for detection, bioptic diagnosis and curative resection of small GEP-NETs of stomach, duodenum, jejuno-ileum, and colon-rectum. Moreover, endoscopic ultrasonography (EUS), associated with high frequency miniprobes, is a valuable procedure in regional staging of lesions of the GI wall and can provide information which has a remarkable impact on therapeutic choices. EUS is still the sole technique, in a substantial number of cases, providing a definitive diagnosis of pancreatic insulinoma and it detects and follows small lesions of the pancreas in patients with Multiple Endocrine Neoplasia type 1 syndrome. EUS should be performed in those cases in which morphological or molecular imaging modalities need to be supported because of negative or dubious results. In this review we describe the applications of endoscopic procedures in the management of GEP-NETs.