Mediterranean diet and colorectal cancer risk: a pooled analysis of three Italian case-control studies

Background: Adherence to the Mediterranean diet (MD) is associated with a reduced risk of several cancers. However, studies conducted in Mediterranean regions are scanty. Methods: To investigate the relation between MD and colorectal cancer risk in Italy, we pooled data from three case-control studies, including a total of 3745 colorectal cancer cases and 6804 hospital controls. Adherence to the MD was assessed using an a priori Mediterranean Diet Score (MDS), based on nine components. Results: Compared with the lowest adherence to the MD (0-2 MDS), the odds ratio (OR) was 0.52 (95% confidence interval (CI) 0.43-0.62) for the highest adherence (7-9 MDS), with a significant inverse trend in risk (P<0.0001). The OR for a 1-point increment in the MDS was 0.89 (95% CI 0.86-0.91). The inverse association was consistent across studies, cancer anatomical subsites and strata of selected covariates. Conclusions: This Italian study confirms a favourable role of MD on colorectal cancer risk.