Consumption of beer and colorectal cancer incidence: a meta-analysis of observational studies

Several meta-analyses and reports from the World Cancer Research Fund supported a risk association between alcohol consumption and colorectal cancer (CRC). However, the association for beer consumption, the common type of alcoholic beverage, remains unclear. We identified studies by a literature search of PUBMED and EMBASE through 30 June 2014. Summary relative risks (SRRs) with their 95 % CIs were calculated with a fixed or random effects model. Twelve case-control and nine cohort studies were included. Compared with non-alcohol drinkers or non-beer drinkers, any beer drinkers were associated with an increased risk of CRC (SRR = 1.20, 95 % CI, 1.06-1.37; p (heterogeneity) < 0.001, I (2) = 73.3 %), which was stronger in the rectum than in the colon. The categorical meta-analysis indicated that heavy (a parts per thousand yen2 drinks/day) beer drinking was related to increased risk of CRC (SRR = 1.37, 95 % CI 1.26-1.49), while light or moderate beer drinking was not. The dose-response analysis demonstrated that an increase of one drink per day in beer consumption was related to an increased risk of CRC (SRR = 1.13, 95 % CI, 1.06-1.21). There was evidence of a potential nonlinear association between beer intake and CRC incidence (p = 0.002 for nonlinearity). The results from this meta-analysis suggest that heavy (a parts per thousand yen2 drinks/day) beer drinking may be associated with increased CRC risk. More researches with improved control of confounding and actual measurement of beer consumption are needed to confirm these findings.