The most abundant of these genes, ADH1B and ADH1C, display decreased expression during progression from adenoma to early and more advanced stage of colorectal carcinomas.
As main effect of genotype, we observed that the ADH1C*2/*2 genotype was associated with a 42% increase in risk of CRC when compared with the ADH1C*1/*1 genotype.
The ADH3 polymorphism showed no measurable association with the risk of colorectal cancer on either overall analysis or stratified analysis with alcohol use.
Therefore, we determined whether polymorphisms in the genes coding for microsomal epoxide hydrolase (EPHX1), NAD(P)H:quinone oxidoreductase (NQO1), cytochrome P450 2E1 (CYP2E1) and alcohol dehydrogenase (ADH3) predispose to the development of CRC.