Chemoprevention of stomach cancer

A varied and balanced diet that is rich in fresh fruit and vegetables and poor in preserved foods is thought to represent the main protection against gastric cancer. Helicobacter pylori infection also appears to have a role in the disease; its eradication therefore represents another promising potential preventive measure. The effect of diet is supposed to be mediated by micronutrients with an antioxidant role, such as ascorbic acid, beta-carotene and alpha-tocopherol, which could act on different phases of the carcinogenic process, interrupting the progression of precancerous lesions towards cancer. The two trials ongoing in Latin America and the one planned in Europe all deal with the effect of antioxidants, with or without H. pylori eradication, on the progression/ regression rate of precancerous lesions of the stomach. The trial in Venezuela has an 80% power to detect a 50% reduction in the net progression of precancerous lesions in the group (from a high-risk population) undergoing a complex antioxidant treatment for 3 years. In this population a case-control study confirmed the protective effect of fresh fruits and vegetables in relation to gastric cancer. Other trials, which aimed to evaluate the chemopreventive potential of micronutrients on other cancer sites, have reported contradictory results concerning gastric cancer risk. When interpreting these results the following should be considered; a possible interaction between H. pylori infection and the antioxidants; the baseline levels of antioxidants in these populations; and the doses and duration of treatment.