Genetic Variants in Alcohol Genes Linked to Cancer

Involved genes affect ADH and ALDH enzymes that have function in alcohol metabolism

MONDAY, Feb. 2 (HealthDay News) -- Several polymorphisms in genes for enzymes involved in ethanol metabolism may influence cancer risk in individuals who consume alcohol, according to a review published in the February issue of The Lancet Oncology.

Nathalie Druesne-Pecollo, Ph.D., of the French National Institute for Agronomical Research in Bobigny, France, and colleagues write that ethanol is chiefly metabolized in the liver. Alcohol dehydrogenases (ADH) oxidize ethanol into acetaldehyde, which is considered a carcinogen in animals. Aldehyde dehydrogenases (ALDH) convert acetaldehyde into acetate, they note.

In most populations, the ADH1B*1 allele (linked to lower acetaldehyde exposure due to a less-active enzyme) is predominant, but the ADH1B*2 allele occurs often in Asian populations, the researchers report. However, drinkers with the ADH1B*2 allele show a decreased risk of cancer of the upper aerodigestive tract. A higher risk in ADH1B*1/*1 homozygotes may be due to a lack of facial flushing while drinking, leading to more alcohol exposure, they write. Asians with the ALDH2*2 allele -- which brings reduced ALDH2 activity -- who drink at least moderately showed increased risk of upper aerodigestive cancers, the report indicates.

"We have reviewed available case-control studies of various genetic polymorphisms and cancer risk. This review provides evidence for a role of ADH1B and ALDH2 polymorphisms on risk of cancer of the upper aerodigestive tract in alcohol drinkers; other data are inconclusive. We have highlighted the need for large multicenter studies and for approaches to the study of multiple polymorphisms," the authors conclude.

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