Toward a dietary prevention of cancer.

I have attempted to address in brief fashion the question as to whether we can recommend a dietary prevention of cancer. This same question was explored in hundreds of pages recently by the large number of advisors assembled by the National Academy of Sciences to assess the animal, cell culture, and human data with regard to diet and cancer (52). My brief assessment has resulted in recommendations to the scientific community not unlike those of the National Academy, but without their clear-cut recommendation against dietary fat. It is obvious that we need a great deal more research on the factors evaluated here, that is, fiber, ascorbic acid, retinoids, the cruciferae, nitrates, alcohol, coffee, saccharine, alpha-tocopherol, aflatoxins, selenium, and saturated and polyunsaturated fats. These factors need assessment not only as they might affect the incidence of any single cancer, but also in relationship to at least the incidence of the cancers that frequently occur in humans. The human epidemiologic inquires have barely begun. We have a few studies of cancer of the colon and of cancer of the lung, and only one or two studies of such important sites as cancer of the larynx, oropharynx, stomach, and breast. Not only have the studies of specific sites been lamentably too few, but only a small number of nutrients have been evaluated. To make matters worse, we have little notion as to the competing risk of different cancers and of other diseases associated with various nutrients. There may be factors that enhance the risk of some diseases at the same time they reduce the risk of others. It is not outside the realm of possibility that the relationship discovered to date with regard to serum cholesterol, heart disease, and cancer may continue to be replicated and may be found related to ingestion of dietary fats. If such should be the case, and the potential is there, we would need to weigh the risks associated with reducing dietary fats for cancer as well as for coronary disease. Questions will need to be answered. For example, what is the optimum level of serum cholesterol to lower the risk of heart disease and at the same time not to enhance the risk of cancer. The same may be said for the association of alcohol with the risk of coronary disease compared to the risk of cancer of the upper alimentary tract.(ABSTRACT TRUNCATED AT 400 WORDS)