Hegemony and cost-effectiveness of endoscopic ultrasound (EUS) in the field of gastroenteropancreatic-neuroendocrine tumors (GEP-NETs).

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are a group of neoplasms arising from the diffuse neuroendocrine system of the gastrointestinal (GI) tract. They often represent a diagnostic challenge because of their little dimensions, the deep localization into the retroperitoneum or in extramucosal sites, the possibility to be multilocated and the heterogeneous patterns of presentation. Endoscopic ultrasound (EUS) is a cost-effective technique that enables to look very definitely at a suspicious mass and at the surrounding area both within the GI wall and in the pancreas, allowing to precisely assess T and N stage. Under EUS-guidance it is possible to obtain tissue samples in order to reach a definitive diagnosis and to establish the tumor grade. In the therapeutic field, EUS is crucial to assess the safety and the feasibility of resective endoscopic techniques for the GI-wall NETs and it can guide local ablative techniques for pancreatic NETs. After treatment, EUS can be successfully useful to assess complete endoscopic resection and to follow-up resected or ablated patients. It is so evident that EUS has a role in the whole route of NETs management, from diagnosis, evaluation, grading and staging assessment, to therapy and consequent follow-up.