This study is part of the EUR-GAST Project, established to elucidate the effects of Helicobacter pylori infection, genetic polymorphisms and environmental factors in gastric cancer etiology in European populations. The EUR-GAST Project is enclosed in a much larger European investigation (European Prospective Investigation into Cancer and Nutrition – EPIC) which is designed to investigate the relationships between diet, nutritional status, lifestyle and environmental factors and the incidence of cancer and other chronic diseases.