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BACKGROUND: Neuroendocrine tumors (NETs) of the duodenum are quite rare representing only 4% of all carcinoid tumors. Limited single-institution case series indicated that ampullary NETs have worse survival than NETs located in the duodenum. The aim of the current study was to evaluate the overall survival (OS) of patients with ampullary NETs compared to patients with duodenal NETs using a population based registry. METHODS: We conducted a retrospective comparative cohort study using the Surveillance, Epidemiology, and End Results (SEER) registry from 1988 to 2009. Patients with pathology confirmed NETs of the duodenum and ampulla of Vater were identified, and overall survival was evaluated using Kaplan-Meier estimates and Cox proportional hazard regression. Multi-variable survival analyses included covariates with p < 0.1 and less than 10% of data missing.
RESULTS: The study cohort included 1360 (92%) patients with duodenal NETs and 120 (8%) with ampullary NETs. Ampullary NETs were larger (median tumor size 18 vs. 10 mm, p<0.001), higher grade (poorly and undifferentiated tumor 42% vs. 12%, p<0.001), and higher SEER historic stage (distant metastasis 18% vs. 9%, p<0.001) than duodenal NETs. Ampullary NETs were also more likely to be resected (78% vs. 60%, p<0.001). OS was significantly worse for patients with ampullary NETs than for patients with duodenal NETs (median OS 98 vs. 143 months; HR 1.38, 95% CI 1.02-1.86, p=0.037). For resected patients (n=878), OS was similar between ampullary and duodenal NETs (median OS 182 vs. 164 months; HR 1.42, 95% CI 0.96-2.09, p=0.078). Using univariate survival analyses, significant predictors for worse OS in resected patients included older age (p<0.001), larger tumor size (p=0.035), higher grade (p<0.001), higher SEER historic stage (p<0.001), and radiation treatment (p=0.003). After adjusting for significant predictors of OS, ampullary NETs had significantly worse OS than duodenal NETs (HR 1.63, 95% CI 1.05-2.53, p=0.031).
CONCLUSIONS: NETs of the ampulla of Vater are more advanced at presentation and have worse OS than duodenal NETs. After controlling for significant predictors of OS, tumor location remained an independent predictor of OS in resected patients.