抄録
This report reviews mechanisms of cancer causation and prevention in the stomach, esophagus and large bowel. Typical risk factors for gastric cancer are the presence of the bacterium Helicobacter pylori and a customary intake of salted pickled foods, that contain specific carcinogens, including 2-chloro-4-methylthiobutanoic acid and others as yet unknown. Cancer of the esophagus in the Orient has similar risk factors as salted pickled foods, but with distinct substrates. The specific carcinogensproduced under those conditions have not yet been identified. Prevention involves lower intake of salted pickled foods and regular consumption of protective vegetables, fruits and tea. Salt acts as an enhancing factor. The etiologic elements associated with proximal colon cancer are not known. For distal colon cancer, the carcinogens may be heterocyclic amines formed during frying, broiling, or cooking of meats or fish.Powerful potentiation occurs as a function of type and amount of dietary fat, generating bile acids acting as promoters in intestinal cancer development through specific mechanisms. Rectal cancer may have similar mechanisms, and in addition alcohol is a risk factor, possibly through generation of acetaldehyde. Intake of insoluble and soluble fibers is protective through increasing stool bulk, and modifying structure of bacterial flora and luminal compounds. Selective alteration of intestinal flora with bifidobacteria reduces colon cancer development appreciably. Vegetables, fruits and tea provide various inhibiting elements reducing risk of distal colon and rectal cancer.Prevention of all types of gastrointestinal cancer is possible through known mechanisms based on appropriate changes in dietary habits.
