Diet Leads to Colon Cancer?
Few occupations have been linked to the development of colon cancer. With the exception of occupational exposure to asbestos, in which an increased risk of colon cancer has been reported to be in the range of twofold to threefold, only slight increases in colon cancer rates have been reported in a smattering of studies of occupational or work hazards.
The association between dietary factors and the development of colon cancer is extraordinarily complex. A positive association has been reported among high meat intake, high saturated fat and cholesterol diets, high caloric intake, dietary fiber, alcohol consumption,increased bowel anaerobic microflora, diets that increase deconjugated fecal bile acid excretion, vitamin D, and calcium content.Undoubtedly, the complexity of the environmental factors, including diet, that are related to colon and rectal cancer is a function of the multiple factors that lead to the development of sporadic polyps: the genetics of at least a two-step process between bowel mucosa initiation and promotion before the polyps occur, the ability of the host to defend itself once polyps occur (because so few of them become malignant), and simple methodologic problems such as the difficulty of designing dietary questionnaires that reliably establish specific dietary intake histories that can be related to polyp and colon cancer rates.
Despite numerous empiric dietary recommendations, at the present, common sense provides as good a set of rules as anything else. High fat intake and high meat intake are probably not good. Although high intake of dietary fiber had been thought to reduce the risk of colon adenoma and cancer, the Nurses Health Study did not demonstrate a protective effect of dietary fiber against colon neoplasia in women.The eventual ability to define precise risks in first-degree relatives of patients with sporadic carcinoma may allow relatively limited populations to specifically avoid specific foodstuffs or supplement their diets. However, the likelihood is much greater that before precise dietary manipulations will be found to prevent colon and rectal cancer, population groups at risk, defined genetically or biochemically, will undergo routine screening of the colon mucosa to diagnose and remove premalignant polyps.
