Objectives: Interest in gastric carcinoid tumors has amplified considerably given the biological establishment of their relationship to gastrin and advances in the elucidation of the pathobiology of such lesions. The recognized propensity of acid-suppressing agents such as the proton pump inhibitor class of drugs to increase plasma gastrin levels has been proposed as a causal relationship in the apparent increase in the identification of such lesions although the increased prevalence of endoscopy and the enhanced awareness of pathologists have also been considered as contributory factors. We sought to examine if there has been an increase in gastric carcinoid incidence time correlative with these parameters.
Methods: Carcinoid tumor cases from the End Results Group (1950-1969) and the Third National Cancer Survey (TNCS) (1969-1971) databases were combined with the most recent release of the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) registry (1973-1999); these three datasets revealed 13715 carcinoid cases, of which 562 were gastric in origin. Age-adjusted analyses as well as population-based gender and race correction ratios were completed in conjunction with United States decennial census data. To allow a finer granularity in incidence trends, the SEER database was divided into early (1973-1991) and late (1991-1999) subsets. RESULTS Since 1950, the percentage of gastric carcinoids among all gastric malignancies has increased from 0.3% to 1.77%. Since 1969, the proportion of gastric carcinoids among all enteric carcinoid lesions has increased from 2.4% to 8.7%. Age-adjusted incidence rates among male, female, black, and white population subsets have all increased since the TNCS time period, with the greatest increase (800%) noted in white females. The male:female ratio has fallen from 0.90 to 0.54. The occurrence of synchronous or metachronous noncarcinoid tumors with gastric carcinoid tumors has decreased by 26% during the course of SEER data collection. The 5-yr survival rate for gastric carcinoids overall has risen from 51% to 63% during the same time period.
Conclusions: Gastric carcinoids have increased in incidence over the last 50 yr. Differential increases in predominance across gender and race subdivisions may reflect genetic-based propensities (or protection) for gastric carcinoid tumors among certain ethnic populations. Increased endoscopic surveillance and associated sophisticated pathological evaluation of gastric biopsies undoubtedly are responsible for some of the observed increase in the incidence of gastric carcinoid tumors. These data allow no specific role to be assigned to the effects of acid-suppressive medications. Nevertheless the role of such agents cannot be discounted at this time since the time frame of the increased incidence is somewhat comparable to the introduction of these agents as is the known biological effect of gastrin on ECL cell proliferation.