Objectives: This paper reviewed analytic epidemiological studies of the major Japanese digestive tract cancers, i.e. esophageal, stomach, colon and rectal. The applicability of the recommendations for prevention of these cancers by the World Cancer Research Fund/American Institute of Cancer Research (W&A) to Japan is considered.
Methods: Papers were searched by the MEDLINE for the period 1966 through 1997. Among them, 43 relevant papers including data from Japan were reviewed.
Results: Results for 11 lifestyle-related factors were considered. Cigarette smoking was a strong and consistent, thus, convincing, risk factor for esophageal cancer, and a possible risk factor for stomach and colorectal cancer. Excessive consumption of alcohol was a convincing risk factor for esophageal cancer, and a possible risk factor for stomach and colorectal cancer. Excessive salt intake was a risk factor supported by some strong evidence but inconsistent; therefore, it is a probable risk factor for stomach cancer and a possible risk factor for colorectal cancer. Low physical activity was a probable risk factor for colorectal cancer. On the other hand, sufficient intake of vegetables, including green-yellow vegetables, and fruits was regarded as a possible protective factor for these cancers.
Conclusions: These observations were mostly consistent with those reported by W&A; therefore the recommendations by W&A for prevention of these cancers may be considered applicable to the current Japanese population.