Date: Sun, 8 Aug 93 9:36:00 EDT From: Robert Sandler Subject: research results Diet and the Risk of Colorectal Adenomas Colorectal adenomas are thought to be the precursors of most colorectal cancers. Although the vast majority colorectal adenomas do not turn into cancer, it is currently thought that as many as 90% of cancers arise from adenomas. If we could determine the cause of adenomas, and if we could prevent them, we could prevent most colorectal cancers. Colorectal cancers are a major problem in the United States. In 1993 there will be more than 150,000 new cases and about 57,000 deaths. When people migrate from low risk countries to high risk countries they acquire higher rates of disease. This important evidence suggests that environmental factors are very important in the etiology of colorectal cancer. Among the environmental factors, diet has received a great deal of attention. In order to explore the possible role of dietary factors in the development of colorectal adenomas, researchers at the University of North Carolina at Chapel Hill interviewed 645 patients who had undergone thorough examinations of their large bowel with a colonoscope. The diets of the 236 with colorectal adenomas were compared to the diets of the 409 without adenomas. Dietary information was obtained through telephone interviews conducted by an experienced dietitian using a detailed food frequency questionnaire. The results, published in the Journal of the National Cancer Institute (1993;85:884-891), showed that carbohydrate intake was inversely related to adenomas in women. Those women whose carbohydrate was in the highest fifth were 60% less likely to develop adenomas than those in the lowest fifth. Intake of fruit and intake of fiber derived from vegetables and fruits were also inversely related in women. Total fat was a risk factor in women. Women in the highest category of fat consumption were 2.7 times more likely to have adenomas. The results were similar for saturated fat. In men the results were generally in the same direction, but were not statistically significant. The data support the hypothesis that a diet high in fat and low in carbohydrates, fruits and fruit and vegetable fiber increase the risk of colorectal adenomas. They further suggest that a diet high in carbohydrates and low in fat, particularly saturated fat, will protect against adenomas and therefore cancers of the large bowel. Keywords: colorectal cancer, diet, vegetables, fiber, carbohydrates.