Treatment of Gastric Neuroendocrine Tumors

Type I gastric neuroendocrine (carcinoid) tumors smaller than 1 cm are indolent with minimal risk for invasion and can be removed with endoscopic mucosal resection.[1-3] Local surgical excision may be performed for rare larger or invasive tumors, but exceptional cases with large multifocal lesions may require gastric resection. Follow-up with yearly endoscopic surveillance and repeated gastroscopy with multiple gastric biopsies is required, and treatment with somatostatin analogues may prevent recurrence.[4]

For type II neuroendocrine tumors, surgery is focused on removing the source of hypergastrinemia, typically by excision of duodenal gastrinomas in patients with multiple endocrine neoplasia type I via duodenotomy with resection of lymph node metastases.[5-7] Because of their generally benign course similar to type I tumors, type II tumors can usually be managed with endoscopic resection (particularly for tumors <1 cm), followed by close endoscopic surveillance.[1,3] Liberal surgical excision or gastric resection with regional lymphadenectomy is performed for larger and multifocal tumors or for those with deep wall invasion or angioinvasion.[3] In patients with multiple tumors, somatostatin analogue treatment may be used to reduce tumor growth, particularly if hypergastrinemia has not been reversed by surgery.[4]

Sporadic type III gastric neuroendocrine tumors, which behave more aggressively than type I and type II tumors, are treated with gastric resection and regional lymphadenectomy.[3] Tumors larger than 2 cm or those with atypical histology or gastric wall invasion are most appropriately dealt with by gastrectomy or radical gastrectomy.[1,8,9] Most of these tumors are metastatic at the time of presentation.[8] The 5-year survival rate may approach 50%, but, in patients with distant metastases, it is only 10%.[10,11]

Subtyping gastric neuroendocrine tumors is helpful in the prediction of malignant potential and long-term survival and as a guide to management.[12] Based on a combined population from 24 Swedish hospitals, one study of 65 patients with gastric neuroendocrine tumors (51 type I, 1 type II, 4 type III, and 9 poorly differentiated [designated as type IV in the study]), management varied according to tumor type. Among all of the patients, 3 received no specific treatment, 40 underwent endoscopic or surgical excision (in 10 cases combined with antrectomy), 7 underwent total gastrectomy, and 1 underwent proximal gastric resection. Radical tumor removal could not be performed in 2 of 4 patients with type III tumors and in 7 of 9 patients with poorly differentiated tumors. For more information, see the Cellular and Pathological Classification of Gastrointestinal Neuroendocrine Tumors section. Five- and 10-year crude survival rates were 96.1% and 73.9%, respectively, for type I tumors (not different from the general population) but only 33.3% and 22.2% for poorly differentiated gastric neuroendocrine tumors.[12][Level of evidence C2]