Potential for personal modification of risk for developing colon cancer.

Research in varied populations, in appropriate animal models, and through other laboratory techniques, in great part fostered through the National Large Bowel Cancer Program of the National Cancer Institute, has provided a reasonable basis for assessing environmental elements as to risk for large bowel cancer. It was noted that the term large bowel cancer needs to be specifically related to subsections of the large bowel that appear to have different risk factors. For the major type of neoplastic disease in the large bowel, that in the descending and sigmoid colon, there is a good association with nutrition and specific nutritional elements. The risk of this type of colon cancer is proportional to the customary dietary fat intake--high in the western world and low in the Orient. It is inversely proportional to stool bulk, itself related to cereal fiber intake. These two major elements are sufficiently secure as to underlying scientific data and understanding of mechanisms to permit utilizing them for personal modification of risk. Thus, a dietary regimen low in total fat, 20% of calories, and higher in cereal fiber, of the order of 30 g per day, are indicated and would serve to reduce risk not only in the general population, but most likely also in patients who have been successfully treated through conventional modalities. There are also suggestions that regular intake of yellow and green vegetables, of foods with calcium salts, selenium, and other micronutrients, lower risk even more. Further research is needed to provide the data base necessary for deliberate interventions with these agents.