Increasing incidence of duodenal neuroendocrine tumors: Incidental discovery of indolent disease?

Background: There has been a marked increase in the recognized incidence of gastroenteropancreatic neuroendocrine tumors (GEP-NETs). Studies have often combined duodenal neuroendocrine tumors (D-NETs) with other small bowel GEP-NETs. As a result, the natural history and clinical ramifications of these D-NETs is poorly understood.

Methods: Patients diagnosed with duodenal "carcinoid" tumors from 1983 to 2010 were identified in the Surveillance Epidemiology and End Results tumor registry.

Results: A total of 1,258 patients were identified. The mean age was 64 years. The majority of patients were male (55.6%), white (55.6%), and had stage I disease (66.2%). Patients meeting inclusion criteria were divided into 2 cohorts: (i) era 1 patients diagnosed with GEP-NETs from 1983 to 2005, and (ii) era 2 those diagnosed from 2005 to 2010. There was a clear increase in the incidence rate of D-NETs from 0.27 per 100,000 in 1983 to 1.1 per 100,000 in 2010 (P < .001). Comparison of patients from the different eras revealed that those in era 2 were more likely than era 1 to present with stage I disease (69.9 vs 57.5%; P < .01) and less likely to present with late-stage disease. The 5-year, disease-specific survival improved for era 2 patients compared with era 1 (89.3 vs 85.2%; P = .05); however, multivariate analysis demonstrated that stage but not era was associated with disease-specific survival.

Conclusion: Prognosis for D-NETs, in contrast with other small bowel NETs, is excellent. There has been a steady increase in the recognized incidence of D-NETs, coincident with the migration to earlier disease stage and improved disease-specific survival.