Background: Previous research has identified a high risk of gastric carcinoma as well as a high prevalence of cancer precursor lesions in rural populations living in the province of Narino, Colombia, in the Andes Mountains. Methods: A randomized, controlled chemoprevention trial was conducted in subjects with confirmed histologic diagnoses of multifocal nonmetaplastic atrophy and/or intestinal metaplasia, two precancerous lesions. Individuals were assigned to receive anti-Helicobacter pylori triple therapy and/or dietary supplementation with ascorbic acid, p-carotene, or their corresponding placebos. Gastric biopsy specimens taken at baseline were compared with those taken at 72 months, Relative risks of progression, no change, and regression from multifocal nonmetaplastic atrophy and intestinal metaplasia were analyzed with multivariate polytomous logistic regression models to estimate treatment effects, All statistical tests were two-sided. Results: All three basic interventions resulted in statistically significant increases in the rates of regression: Relative risks were 4.8 (95% confidence interval [CI] = 1.6-14.2) for anti-H. pylori treatment, 5.1 (95 % CI = 1.7-15.0) for p-carotene treatment, and 5.0 (95% Cf = 1.7-14.4) for ascorbic acid treatment in subjects with atrophy. Corresponding relative risks of regression in subjects with intestinal metaplasia were 3.1 (95% CI = 1.0-9.3), 3.4 (95% CI = 1.1-9.8), and 3.3 (95% CI = 1.1-9.5), Combinations of treatments did not statistically significantly increase the regression rates. Curing the H. pylori infection (which occurred in 74% of the treated subjects) produced a marked and statistically significant increase in the rate of regression of the precursor lesions (relative risks = 8.7 [95 % CI = 2.7-28.2] for subjects with atrophy and 5.4 [95% CI = 1.7-17.6] for subjects with intestinal metaplasia), Conclusions: In the very high-risk population studied, effective anti-tl; pylori treatment and dietary supplementation with antioxidant micronutrients may interfere with the precancerous process, mostly by increasing the rate of regression of cancer precursor lesions, and may be an effective strategy to prevent gastric carcinoma.
