Abstract
Alcohol intake is positively associated with the risk of upper aerodigestive tract (UAT) cancer. The genes that encode alcohol-metabolizing enzymes, primarily alcohol dehydrogenases (ADH) and aldehyde dehydrogenases (ALDH), are polymorphic. In Caucasians, significant associations between polymorphisms in ADH1B (rs1229984) and ADH1C (rs698 and rs1693482), and UAT cancer have been observed, despite strong linkage disequilibrium among them. Moreover, UAT cancer was significantly associated with rs1573496 in ADH7, and not with rs1984362 in ADH4. However, little evidence is available concerning ADH4 or ADH7 polymorphisms in Asian populations. We conducted a matched case-control study to clarify the role of ADH polymorphisms in a Japanese population. Cases and controls were 585 patients with UAT cancer and 1,170 noncancer outpatients. Genotyping for ADHs and ALDH2 was done using TaqMan assays. Associations between polymorphisms and UAT cancer were assessed by odds ratios and 95% confidence intervals using conditional logistic regression models that adjusted for age, sex, smoking, drinking, and ALDH2. Adjusted odds ratios were significant for rs4148887 and rs3805322 in ADH4, rs1229984 in ADH1B, rs698 and rs1693482 in ADH1C, and rs284787, rs1154460, and rs3737482 in ADH7. We also observed that ADH7 rs3737482 and ADH4 rs4148887 had independently and statistically significant effects on UAT cancer. The magnitude of effect of these ADH polymorphisms was greater in subjects who were heavy drinkers, heavy smokers, and had esophageal cancer. These findings show that multiple ADH gene polymorphisms were associated with UAT cancer in this Japanese population. Further studies in various ethnicities are required.
Highlights
Alcohol consumption is one of the most important risk factors for upper aerodigestive tract (UAT) cancer [1]
Because polymorphisms in ADH4 were in linkage disequilibrium (LD) with other neighboring loci, we evaluated the odds ratio (OR) in subjects with ADH1B homozygous major alleles
We found that multiple alcohol dehydrogenase enzymes (ADH) gene polymorphisms showed significant associations with UAT cancers
Summary
Alcohol consumption is one of the most important risk factors for upper aerodigestive tract (UAT) cancer [1]. Acetaldehyde, an oxidative product of ethanol, is suspected to be a major carcinogen behind this association [2]. Because the genes that encode these representative ethanol-metabolizing enzymes contain polymorphisms that modulate individual differences in ethanol- and acetaldehyde-oxidizing capacity [4], they have been hypothesized to explain individual differences in UAT cancer susceptibility. The association between polymorphisms in some of these ADH genes and UAT cancers has been investigated, most studies have focused on ADH1B rs1229984 or ADH1C The largest, most comprehensive epidemiologic study recently conducted in Europe showed that the effect of ADH1C rs1693482 and rs698 was independent of that of ADH1B rs1229984, despite strong linkage disequilibrium (LD) among them [14].
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