Background: Epidemiologic studies have generally reported positive associations between alcohol consumption and risk for colorectal cancer. However, findings related to specific alcoholic beverages or different anatomic sites in the large bowel have been inconsistent.
Objective: To examine the relationship of total alcohol intake and intake from specific beverages to the incidence of colorectal cancer and to evaluate whether other potential risk factors modify the association.
Design: Pooled analysis of primary data from 8 cohort studies in 5 countries.
Setting: North America and Europe.
Participants: 489,979 women and men with no history of cancer other than nonmelanoma skin cancer at baseline.
Measurements: Alcohol intake was assessed in each study at baseline by using a validated food-frequency questionnaire.
Results: During a maximum of 6 to 16 years of follow-up across the studies, 4687 cases of colorectal cancer were documented. In categorical analyses, increased risk for colorectal cancer was limited to persons with an alcohol intake of 30 g/d or greater (approximately > or =2 drinks/d), a consumption level reported by 4% of women and 13% of men. Compared with nondrinkers, the pooled multivariate relative risks were 1.16 (95% CI, 0.99 to 1.36) for persons who consumed 30 to less than 45 g/d and 1.41 (CI, 1.16 to 1.72) for those who consumed 45 g/d or greater. No significant heterogeneity by study or sex was observed. The association was evident for cancer of the proximal colon, distal colon, and rectum. No clear difference in relative risks was found among specific alcoholic beverages.
Limitations: The study included only one measure of alcohol consumption at baseline and could not investigate lifetime alcohol consumption, alcohol consumption at younger ages, or changes in alcohol consumption during follow-up. It also could not examine drinking patterns or duration of alcohol use.
Conclusions: A single determination of alcohol intake correlated with a modest relative elevation in colorectal cancer rate, mainly at the highest levels of alcohol intake.