摘要：

There is a general agreement that dietary factors, particularly dietary fat, significantly influence the pathagenesis of large bowel cancer. The following hypotheses on the etiology of colon cancer are suggested: 1)conversion of cholesterol and δ5−7-dehydrocholesterol, which are normally present in colonic contents and mucosa, to reactive metabolites that act as carcinogens, may be an important step in colon carcinogenesis; 2)dietary fat changes the concentration of bile acids and also the metabolic activity of colonic bacteria, which may produce tumorigenic compounds from bile acids; 3) mucosal and/or luminal conversion of cholesterol to its epoxide may be of etiologic significance; and 4) diet also influences mixed-function oxidases, which could play a role in modifying colon carcinogenesis. Today's challenges to biomedical scientists and clinical investigators involved in colon cancer are as follows: 1) the animal experimentor should design and effectively relate animal models to the human setting; 2) it should be found whether it is possible for the fecal constituents of an individual on an American diet to be made similar to those of individuals on a Japanese diet, and, if so, what degree of dietary modification is required?; 3) it should be found whether solitary polyps could be reduced in size by strict dietary modification; 4) regarding managerial preventive medicine, it should be decided whether it is recommended to reduce the fat and cholesterol content of our staple diet; and 5) with regard to individual preventive medicine, people should be aware of calorie excesses, and of the fat and cholesterol content of their diet from early in life onward.

展开