The association of the healthy eating index with risk of colorectal cancers (overall and by subsite) among Canadians

Abstract

BackgroundHealthy dietary patterns characterized by high intake of fruits and vegetables, grains/cereals, and lean meat/fish, and low intake of red/processed meats and refined carbohydrates, have been shown to be associated with reduced risk of colorectal cancer, but evidence regarding their association with colorectal cancer subsites is limited. Hence, this study was conducted to assess the association of a healthy dietary pattern, as reflected in the Healthy Eating Index (HEI) (a composite score based on consumption of various food groups), with risk of colorectal cancer, overall and by subsite. MethodsWe conducted a case-cohort study in the Canadian Study of Diet, Lifestyle and Health (CSDLH). The study included all cases of incident colorectal cancer in the entire cohort, and an age-stratified subcohort of 3185 women and 2622 men. Cox regression models were used to estimate hazard ratios (HR) for the association between the HEI and the risk of colorectal cancer, overall and by subsite. We also assessed the association by sex and by selected metabolic factors. ResultsFor both sexes combined, the highest quintile of the HEI score was inversely associated with risk of colorectal cancer, colon cancer and proximal colon cancer (HR: 0.65; 95% CI: 0. 49–0.85, HR: 0.60, 95% CI: 0.44–0.83 and HR: 0.54, 95% CI: 0.35–0.85, respectively). However, these associations were mostly observed among men (HR: 0.56; 95% CI: 0.38–0.81, HR: 0.44, 95% CI: 0.28–0.69 and HR: 0.26; 95% CI: 0.12–0.56, for colorectal cancer, colon cancer and proximal colon cancer, respectively; p-interactions=0.029, 0.032 and 0.063, respectively). An inverse association was also observed between the HEI and risk of colorectal cancer among normal weight participants, overweight/obese participants, non-smokers, non-alcohol drinkers and participants who were physically inactive. ConclusionA healthy dietary pattern may reduce risk of colorectal cancer, particularly among men.