Is there evidence that diet affects colorectal cancer risk?
Yes. Colorectal cancer rates vary widely from country to country; studies of people who emigrate show that as they adopt a diet of the new country, their colorectal cancer risk becomes more like the country to which they moved. This shows that while genetic susceptibility (heredity) may play a role in colorectal cancer, outside (environmental) factors also influence risk. Studies in laboratory animals have shown that fat increases and fiber decreases risk of colorectal tumors. Many epidemiologic studies looking at what people eat (observational studies) have suggested that red meat and dietary fat increase colorectal cancer risk while vegetables, dietary fiber, and some nutrients lower the risk. For more detailed information, see the Prevention of Colorectal Cancer statement on NCI’s Web site at http://www.cancer.gov and go to the Genetics, Causes, Risk Factors and Prevention category. • Are other large trials looking at the role of diet in cancer prevention? The Women’s Health Initiat
