Type I gastric carcinoids smaller than 1 cm are indolent with minimal risk for invasion and can be removed with endoscopic mucosal resection.[1,2,3] 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 analogs may prevent recurrence.
For type II carcinoids, 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.[5,6,7] 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. In patients with multiple tumors, somatostatin analog treatment may be used to reduce tumor growth, particularly if hypergastrinemia has not been reversed by surgery.
Sporadic type III gastric carcinoids, which behave more aggressively than type I and type II tumors, are treated with gastric resection and regional lymphadenectomy. 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. The 5-year survival may approach 50%, but, in patients with distant metastases, it is only 10%.[10,11]
Subtyping gastric carcinoids is helpful in the prediction of malignant potential and long-term survival and is a guide to management. Based on a combined population from 24 Swedish hospitals, one study of 65 patients with gastric carcinoids (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 and 7 of 9 patients with poorly differentiated tumors. (Refer to the Cellular and Pathologic Classification of Gastrointestinal Carcinoid Tumors section of this summary for more information.) 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.[Level of evidence: 3iiD].