Genetic modulation of ADH1B and ALDH2 polymorphisms with regard to alcohol and tobacco consumption for younger aged esophageal squamous cell carcinoma diagnosis

Genetic variants in alcohol dehydrogenase-1B (ADH1B) and aldehyde dehydrogenase-2 (ALDH2) genes modulate acetaldehyde removal upon alcohol ingestion. Although these genetic vulnerabilities have been linked to higher esophageal squamous cell carcinoma (ESCC) risks, it is unclear whether they also determine the time of malignancy presentation. The purpose of this investigation was to unravel genotoxic effects of the two alcohol-metabolizing genes with regard to alcohol and tobacco consumption on the age at ESCC diagnosis and tumor dissemination. ADH1B/ALDH2 genotyping was performed on lymphocyte DNA specimens taken from 406 consecutively registered incident patients with pathology-proven ESCC. To fully utilize individual genetic and survival information, survival analyses and gene-longevity applied approaches were introduced. Among heavy drinkers, the ADH1B Arg/Arg (55 years) and ALDH2 Glu/Lys genotypes (54 years) were found to confer a 15 and 16 years earlier carcinoma diagnosed age than His/His and Glu/Glu nondrinkers (both 70 years), respectively. For drinkers, 1-year age advancement was, separately, associated with a 0.977 and 0.953-fold stepwise reduced likelihood of being ADH1B Ara homozygote and ALDH2 Lys variant. Noticeably elevated hazard-ratio (HR) for drinkers of ADH1B slow-form genotype and ALDH2 inactive-form allele were identified in smokers (HR = 2.3-2.6), but no in nonsmokers. In smokers, appreciably higher cumulative cancer onset risks were correspondingly recognized from the age of 45 and 49 upward among any + Lys allele and Arg/Arg + Glu/Glu combined-ADH1B/ALDH2-genotype drinkers than nondrinkers. In conclusion, consumption of tobacco and alcohol, coupled with genetic susceptibilities associated with acetaldehyde elimination, as modulated by ADH1B and ALDH2 genotypes, determines a substantial magnitude of tumorigenetic effect on earlier age ESCC diagnosis. (C) 2009 UICC