Another study measuring salivary acetaldehyde levels twice with a 1 h interval in intoxicated Japanese alcohol-dependent men found that acetaldehyde was higher in the saliva of ALDH2*1/*2 than in that of the ALDH2*1/*1 group, providing a possible mechanistic explanation for the increased risk for UADT cancers in this sub-population [56]. This evidence concerns the gene ALDH2 and cancer.