Italian mediterranean index and risk of colorectal cancer in the Italian section of the EPIC cohort

Colorectal cancer is among the commonest cancers worldwide. Dietary factors have been linked to colorectal cancer risk, however, few studies have evaluated the relationship between a priori dietary patterns and colorectal cancer risk. We evaluated the effect of adherence to a Mediterranean dietary pattern, as measured by the Italian Mediterranean Index, on the risk of colorectal cancer in the 45,275 participants of the Italian section of the EPIC study who completed a dietary questionnaire. Hazard ratios (HRs) with 95% confidence intervals (CIs) for colorectal cancer in relation to categories of Italian Mediterranean Index score were estimated by multivariate Cox models adjusted for known risk factors, on the whole cohort, on men and women and according to cancer subsite. During a mean follow-up of 11.28 years, 435 colorectal cancer cases were identified. The Italian Mediterranean Index was inversely associated with colorectal cancer risk (HR: 0.50; 95% CI: 0.35-0.71 for the highest category compared to the lowest, P-trend: 0.043). Results did not differ by sex. Highest Italian Mediterranean Index score was also significantly associated with reduced risks of any colon cancer (HR: 0.54, 95% CI: 0.36-0.81), distal colon cancer (HR: 0.44, 95% CI: 0.26-0.75) and rectal cancer (HR: 0.41, 95% CI: 0.20-0.81), but not of proximal colon cancer. These findings suggest that adherence to a Mediterranean diet (as measured by the Italian Mediterranean Index) protects against colorectal cancer in general but not against cancer developing in the proximal colon. What's new? The Mediterranean diet has been associated with beneficial effects on cancer risk. Here, in the first prospective study to assess the relationship between Mediterranean diet and colorectal cancer risk in a European country, high adherence to the diet was found to protect against the disease, with the exception of proximal colon cancer. The findings reveal that a diet high in fruits, vegetables, and pulses, which are rich in dietary fiber, may reduce colorectal cancer risk.