Diet and chemoprevention of colon polyps and colorectal cancer.

Clinical trials in colorectal cancer prevention are based on carcinogenesis research and epidemiologic observations that relate certain macronutrients, micronutrients, non-nutritive factors in foods, and synthetic chemicals to colon neoplasms. These factors appear to act at various points along the putative normal mucosa --> adenomatous polyp --> cancer sequence. This gives an opportunity to develop innovative clinical trails, both in agent selection and in the use of intermediate markers. Clinical colorectal cancer prevention trials are not in progress that employ dietary fiber, a variety of vitamins and minerals and several synthetic drugs, especially the NSAIDs. Most of these trials use the adenomatous polyp as a surrogate marker for colon cancer, thereby reducing trial duration, number of subjects required and overall expense. This paper is a brief review of the basic and epidemiologic background for colorectal cancer prevention trials and their current status.