The use of epidemiology, scientific data, and regulatory authority to determine risk factors in cancer of some organs of the digestive system: 4. Colon cancer

Abstract

Colon cancer accounts for over 10% of all cancers diagnosed from 1973 to 1976 in the United States. Many factors have been identified as having a role in its etiology, including the intestinal microflora, colonic mutagens, bile acids, cholesterol, estrogens, and diet. The evidence supporting or refuting the importance of each of these factors and others is discussed. Dietary factors appear to be the most important risk determinants for colon cancer. In particular, a high-fat, low-fiber diet has been most consistently incriminated as a promoting agent of this cancer. The incidence of colon cancer and consumption of total fat and animal protein are highly correlated internationally. However, further epidemiologic studies have given equivocal results. A high-fiber diet has been proposed as being protective against colon cancer although the mechanism of protection remains unclear. A major correlational study has shown that dietary fiber consumption was higher in areas with low incidence of colon cancer than in those areas with high incidence. A few case-control studies have been supportive of the fiber hypothesis but many more have shown no difference among cases and controls in their fiber consumption. More epidemiological studies are needed to clarify the role of diet in the etiology of colon cancer. Before a dietary change is recommended, the competing risks of other cancers and other diseases should be extensively researched.