This project evaluates the endpoints to determine the status and the evolution of the lesions of the gastric mucosa utilizing histopathological, immunochemical and molecular biology techniques. Biopsies taken from 8 specific locations in the gastric mucosa in patients from Colombia and New Orleans will be assigned a global diagnosis based on the most advanced lesion and detailed assessment of the following parameters" polymorphonuclear, and mononuclear leukocytic infiltration, damage to epithelial cells, atrophy, metaplasia, mucins, Lewis antibodies, Ki 67 labelling index, inducible nitric oxide synthase, nitrotyrosine, apoptosis, p53 abnormalities, TPR-MET expression and microsatellite destabilization. The techniques for the utilization of these markers are described in the text and are thoroughly familiar to the investigators. The different interventions described in the other projects, especially anti-Helicobacter pylori therapy and administration of antioxidants are directed to modify the phenotypic events in the precancerous process. The markers chosen are intended to evaluate those changes with state of the art techniques in pre- and post-intervention biopsies. Each marker will be evaluated independently and combinations of them will be designed and tested to develop measures of change of the precancerous process in terms of single and combined scores.