Neuroendocrine Tumor in Upper Gastrointestinal Tract

ABSTRACT

Gastric neuroendocrine tumor (GNET) is rare, but increasing in incidence. GNET may be classified into three types on the basis of the background pathology. Type I GNET is related to autoimmune atrophic gastritis and hypergastrinemia. Type II is related to multiple endocrine neoplasia (MEN)-1, Zollinger-Ellison syndrome and hypergastrinemia and sporadic Type III is not related to any background pathology. Type I GNETs can be considered as benign tumors with unusual metastases. However, type II may be related to distant metastases, which is also common in type III GNETs. Type I and type II lesions can be treated by endoscopic excision or somatostatin analogues whereas surgical treatment should be considered for type III lesions. Hypergastrinemia is an essential precondition for the evolution of type I and II lesions, but hypergastrinemia alone is not enough for explanation of tumorigenesis. Furthermore, the pathogenesis of type III neuroendocrine tumors is still poorly understood. Despite improvements in our knowledge of GNET pathogenesis in diagnostic approach and treatment, further investigations and large scale clinical studies are warranted.