Alcohol intake and colorectal cancer risk: a dose-response meta-analysis of published cohort studies

The epidemiologic evidence support that alcohol intake might be associated with increased colorectal cancer risk. However, the results by anatomic site in the large bowel are inconsistent. We conducted a meta-analysis of prospective cohort studies published between 1990 and June 2005 on the relationship between alcohol intake and colon and rectal cancer. We quantified associations with colon and rectal cancer using meta-analysis of relative risk (RR) associated to the highest versus the lowest category of alcohol intake and meta-analysis of study-specific dose-response slopes using fixed or random effect models depending on the heterogeneity of effects among studies. Sixteen prospective cohort studies including more than 6,300 patients with colorectal cancer were eligible for inclusion. High alcohol intake was significantly associated with increased risk of colon (RR = 1.50; 95% CI = 1.25, 1.79) and rectal cancer (RR = 1.63; 95% CI = 1.35, 1.97) when comparing the highest with the lowest category of alcohol intake, equivalent to a 15% increase of risk of colon or rectal cancer for an increase of 100 g of alcohol intake per week. The relationship did not differ significantly by anatomical site (colon, rectum). Using meta-regression analysis, we identified geographical area where the study was conducted as a possible source of between-study heterogeneity of effects among studies. Lifestyle recommendations for prevention of colorectal cancer should consider limiting alcohol intake.