Tomatoes and risk of digestive-tract cancers

In view of the persisting uncertainty concerning possible mechanisms by which high vegetable and fruit intake decreases cancer risk, foods with divergent values for potentially important micronutrients are a priority for investigation. Tomatoes are low in beta-carotene, but high in lycopene, an active antioxidative agent. In order to assess the effect of tomatoes on risk of cancers of the digestive tract, data were analyzed from an integrated series of case-control studies conducted between 1985 and 1991 in northern Italy, where tomato intake is high but, also, heterogeneous. The overall dataset included the following histologically confirmed cancer cases: oral cavity and pharynx, 314; esophagus, 85; stomach, 723; colon, 955; and rectum, 629; and a total of 2,879 controls admitted to hospital for acute non-neoplastic or non-digestive conditions, unrelated to long-term dietary modifications. Multivariate odds ratios (OR) and 95% confidence interval (CI) for subsequent quartiles of intake of raw tomatoes were derived, after allowance for age, sex, study center, education, smoking and drinking level, and tertile of total caloric intake. There was a consistent pattern of protection for all sites (OR in the upper quartile ranging between 0.4 and 0.7), most notably for gastrointestinal neoplasms. All trends in risk were highly significant. The beneficial effect of raw tomatoes in this population may be partly due to the fact that they constitute perhaps the most specific feature of the Mediterranean diet. However, if it is true that tomatoes protect against digestive-tract cancers, this is of interest from both a scientific and a public health viewpoint.