Clinical Aspects of Gastric and Duodenal Neuroendocrine Neoplasms

Abstract

With the development of endoscopy, the incidence of gastric and duodenal neuroendocrine neoplasms (NENs) has increased in recent decades. In the 2010 World Health Organization (WHO) classification, well-differentiated NENs were classified into NET G1 or G2, which is equivalent to the carcinoid tumor. Poorly differentiated NENs were named neuroendocrine carcinoma (NEC). Gastric NENs are classified into four types in accordance with their characteristics. Type 1 generally appears as multiple polypoid tumors at the fundus and corpus and takes a benign course. Type 2 has morphologically similar characteristics to type 1 and is associated with Zollinger-Ellison syndrome. Endoscopic treatment should be considered for cases in which the tumor is less than 2 cm and confined to mucosa and submucosa. In type 1 and type 2 accompanying hypergastrinemia, if the tumor was less than or equal to 1 cm, observation without endoscopic resection may be considered. Type 3 occurs sporadically and requires aggressive surgical treatment, including gastric resection and lymph node dissection due to poor prognosis. Poorly differentiated neuroendocrine carcinomas were classified as type 4. Although type 4 tumors are usually inoperable, surgery is sometimes performed with the aim of reducing tumor volume. Somatostatin analog, interferon alpha, and cytotoxic chemotherapy can be used with metastatic NENs. Duodenal NENs are rare compared to stomach NENs. The prognosis of duodenal NENs depends on their size. Endoscopic resection can be performed in small duodenal NENs. Surgery, including Whipple’s procedure, should be considered in large tumors.