Investigating diet and colorectal cancer associations

Nutrition Research Newsletter, Nov, 2004

Colorectal cancer is the second most common cancer in the United States and Europe. It has been suggested that up to 80% of the differences in colorectal cancer rated between countries may be attributable to nutrition-related factors, especially the rates of overweight and obese individuals. Evidence suggests that the risk is increased by high intakes of meat and fat, and that risk is decreased by high intakes of fruits and vegetables, dietary fiber, folate, and calcium, but these hypotheses have not been confirmed. Previous results have shown more consistent and stronger associations between certain dietary patterns and colorectal cancer than between individual nutrients or foods and colorectal cancer.

The goal of the Dietary Patterns and Cancer (DIETSCAN) project was to develop and apply a common methodologic approach to study dietary patterns and cancer in four European cohorts: the Alpha-Tocopherol Beta-Carotene Cancer Prevention Study (ATBC; Finland), the Netherlands Cohort Study (NLCS) on Diet and Cancer, the Swedish Mammography Cohort (SMC), and the Ormoni e Dieta nella Eziologia dei Tumori (ORDET; Italy), and to determine whether the associations of those dietary patterns with cancer are consistent across cultures. Factor analysis was selected as the common method and was applied a posteriori to the dietary data collected in each cohort. The current study reports findings from the factor analysis of dietary patterns end their association with colon and rectal cancer in three of the cohorts (ATBC, NLCS, and SMC) that provided colorectal cancer data.

The cohorts were established between 1985 and 1992; follow-up data were obtained from national cancer registries. All participants completed semi-quantitative food-frequency questionnaires at baseline.

Exploratory factor analysis, conducted within each cohort, identified 3-5 stable dietary patterns. Two dietary patterns--Vegetables and Pork, Processed Meats, Potatoes (PPP)--were common across all cohorts. Following adjustment for potential confounders, PPP was associated with an increased risk of colon cancer in the SMC women (quintile cmultivariate relative risk: 2.21; 95% CI: 1.07, 4.57; P for trend = 0.05). Neither pattern was associated with the risk of colon or rectal cancer in the NLCS women and men.

While there are certain dietary patterns consistent across Europe, there was no conclusive evidence of risk of colon cancer associated with these patterns.

L. Dixon, H. Balder, M. Virtanen, et al. Dietary patterns associated with colon and rectal cancer: results from the Dietary Patterns and Cancer (DIETSCAN) project. Am J Clin Nutr; 80:1003-1011 (October, 2004). [Correspondence: LB Dixon, Department of Nutrition, Food Studies, and Public Health, New York University, 35 West 4th Street, 10th Floor, New York, NY 10012. E-mail: beth.dixon@nyu.edu].