Alcohol ingestion and colorectal neoplasia: A meta-analysis based on a Mendelian randomization approach

Aim Observed associations of alcohol with colorectal cancer are prone to distortion by confounding and reverse causation. A Mendelian randomization approach provides an unbiased estimate of the association using the aldehyde dehydrogenase 2 (ALDH2) variant as a surrogate of alcohol exposure. Method A meta-analysis was performed to assess the association between the ALDH2 genotype and colorectal neoplasia, using the ALDH2 genotype as a marker of alcohol intake. Results The pooled odds ratio (OR) of colorectal neoplasia was 1.31 (95%CI, 1.01-1.70) for the Glu/Glu vs the Lys/Lys genotype. There was no evidence of interstudy heterogeneity (P=0.12, I2=42.7). The overall risk for Glu/Lys heterozygotes relative to Lys/Lys homozygotes (under a fixed-effects model) was 1.13 (95%CI, 0.86-1.48). There was no evidence of publication bias for Glu/Glu or Glu/Lys analysis. Conclusion The result supports the role of alcohol in colorectal carcinogenesis based on a Mendelian randomization approach. © 2011 The Authors. Colorectal Disease