The etiology of gastric cancer

We review recent evidence concerning risk factors for gastric cancer. An overview of analytical studies shows convincing evidence of a protective effect of fruit and vegetables. The specific protective constituents have not been firmly established, but micronutrients, especially ascorbic acid, are probably of importance. Other dietary factors that show a consistent pattern of effect in different studies are the moderate risks associated with high intake of preserved foods and salt. Evidence also indicates that gastric cancer is associated with tobacco consumption, although even in continuing heavy smokers the risk does not exceed two fold. Another non-dietary factor of potential importance is infection with the bacterium, Helicobacter (Campylobacter) pylori. The model of Correa and co-workers currently offers the best working hypothesis to explain the etiology of gastric cancer. Although the endogenous synthesis of N-nitroso compounds is central to the model, it is not yet clear what the rate-limiting steps are. Exposure to nitrate per se does not directly cause gastric cancer.