Alcohol dehydrogenase 3 genotype modification of the association of alcohol consumption with breast cancer risk

Influence of alcohol consumption and alcohol metabolism variants on breast cancer risk among Black women: results from the AMBER consortium

BACKGROUND

Moderate to heavy alcohol consumption is associated with an increased risk of breast cancer. The etiologic role of genetic variation in genes involved in ethanol metabolism has not been established, with little information available among women of African ancestry.

METHODS

Our analysis from the African American Breast Cancer Epidemiology and Risk (AMBER) Consortium included 2889 U.S. Black women who were current drinkers at the time of breast cancer diagnosis (N cases = 715) and had available genetic data for four ethanol metabolism genomic regions (ADH, ALDH, CYP2E1, and ALDH2). We used generalized estimating equations to calculate genetic effects, gene* alcohol consumption (≥ 7drinks/week vs. < 7/week) interactions, and joint main plus interaction effects of up to 23,247 variants in ethanol metabolism genomic regions on odds of breast cancer.

RESULTS

Among current drinkers, 21% of cases and 14% of controls reported consuming ≥ 7 drinks per week. We identified statistically significant genetic effects for rs79865122-C in CYP2E1 with odds of ER- breast cancer and odds of triple negative breast cancer, as well as a significant joint effect with odds of ER- breast cancer (≥ 7drinks per week OR = 3.92, < 7 drinks per week OR = 0.24, p_joint = 3.74 × 10^-6). In addition, there was a statistically significant interaction of rs3858704-A in ALDH2 with consumption of ≥ 7 drinks/week on odds of triple negative breast cancer (≥ 7drinks per week OR = 4.41, < 7 drinks per week OR = 0.57, p_int = 8.97 × 10^-5).

CONCLUSIONS

There is a paucity of information on the impact of genetic variation in alcohol metabolism genes on odds of breast cancer among Black women. Our analysis of variants in four genomic regions harboring ethanol metabolism genes in a large consortium of U.S. Black women identified significant associations between rs79865122-C in CYP2E1 and odds of ER- and triple negative breast cancer. Replication of these findings is warranted.

Alcohol and breast cancer

Breast cancer is one of the main causes of death in women worldwide. In women, breast cancer includes over half of all tumours caused by alcohol. This paper discusses both ethanol metabolism and the mechanisms of mammary tumourigenesis caused by alcohol. Numerous signalling pathways in neoplastic transformation following alcohol consumption in women have been presented. In addition, primary and secondary prevention, phytochemicals, synthetic chemicals, specific inhibitors of enzymes and selective receptor modulators have been described.

Association between alcohol consumption and mammographic density: a hospital-based cross-sectional study

BACKGROUND

Mammographic density (MD), the proportion of radiological dense breast, has been reported to be a strong risk factor for breast cancer in many studies. Epidemiological evidence indicates that alcohol consumption increases the risk of breast cancer. In Western countries, a positive association between alcohol consumption and MD has been reported.

METHODS

To investigate the effect of alcohol consumption on MD, we conducted a cross-sectional analysis of healthy women enrolled in a breast cancer screening program at the Ebina Health Service Center, Japan, in 2012, comprising 477 premenopausal women and 308 postmenopausal women. Alcohol consumption was assessed using a self-report questionnaire. Unconditional logistic regression was applied to calculate the odds ratio (OR) and 95% confidence intervals (CI) while adjusting for confounders.

RESULTS

The study included 497 women with high breast density (HD group) and 288 women with low breast density (LD group). In all women, multivariate analysis revealed that the OR for HD was significantly increased among women with the highest alcohol intake (≥ 140 g/week of ethanol) compared with abstainers (OR 2.1, 95% CI 1.2-3.9 p = 0.01). The linear trend with increasing alcohol consumption was statistically significant (p = 0.009).

CONCLUSION

MD was positively associated with alcohol consumption in Japanese women.

Alcohol drinking, ADH1B and ADH1C genotypes and the risk of postmenopausal breast cancer by hormone receptor status: the Netherlands Cohort Study on diet and cancer

Alcohol consumption has consistently been shown to increase breast cancer (BC) risk. This association may be modified by single nucleotide polymorphisms (SNPs) in alcohol dehydrogenase (ADH) isoenzymes ADH1B and ADH1C. The Netherlands Cohort Study comprises 62 573 women, aged 55-69 years at baseline (1986). Follow-up for postmenopausal BC for 20.3 years was available. Genotyping of six tag SNPs in ADH1B and ADH1C was performed on DNA from toenails. A case-cohort approach was used for analysis (complete data available for nsubcohort = 1301; ncases = 1630). Cox regression models for postmenopausal BC were applied to determine marginal effects of alcohol intake and SNPs using a dominant genetic model, as well as multiplicative interaction of the two. Results were also obtained for subtypes by estrogen receptor (ER) and progesterone receptor (PR) status. Multiple testing was adjusted for by applying the false discovery rate (FDR). Alcohol intake (categorical) increased the risk of postmenopausal BC (Ptrend = 0.031). Trends for ER and PR subgroups followed a similar pattern. Continuous modeling of alcohol resulted in a hazard rate ratio (HR) for overall postmenopausal BC of 1.09 (95% confidence interval: 1.01-1.19) per 10 g/day of alcohol. SNPs were not associated with BC risk. No effect modification of the alcohol-BC association by SNP genotype was seen after FDR correction in overall BC and ER/PR subgroups. In conclusion, alcohol consumption was shown to increase the risk of postmenopausal BC. This association was not significantly modified by common SNPs in ADH1B and ADH1C, neither in overall BC nor in hormone receptor-defined subtypes.

Alcohol Intake and Breast Cancer Risk: Weighing the Overall Evidence

Moderate alcohol consumption has been linked to an approximate 30-50% increased risk in breast cancer. Case-control and cohort studies have consistently observed this modest increase. We highlight recent evidence from molecular epidemiologic studies and studies of intermediate markers like mammographic density that provide additional evidence that this association is real and not solely explained by factors/correlates of the exposure and outcome present in non-randomized studies. We also review evidence from studies of higher risk women including BRCA1 and BRCA2 mutation carriers. Given the incidence of heart disease is higher than breast cancer and modest alcohol consumption is associated with reduced risk of heart disease, we examine the latest evidence to evaluate if alcohol reduction should be targeted to women at high risk for breast cancer. We also review the most recent evidence on the effect of alcohol use on tumor recurrence and survival for those diagnosed with breast cancer.

Ethanol metabolism and its effects on the intestinal epithelial barrier

Ethanol is widely consumed and is associated with an increasing global health burden. Several reviews have addressed the effects of ethanol and its oxidative metabolite, acetaldehyde, on the gastrointestinal (GI) tract, focusing on carcinogenic effects or alcoholic liver disease. However, both the oxidative and the nonoxidative metabolites of ethanol can affect the epithelial barrier of the small and large intestines, thereby contributing to GI and liver diseases. This review outlines the possible mechanisms of ethanol metabolism as well as the effects of ethanol and its metabolites on the intestinal barrier. Limited studies in humans and supporting in vitro data have indicated that ethanol as well as mainly acetaldehyde can increase small intestinal permeability. Limited evidence also points to increased colon permeability following exposure to ethanol or acetaldehyde. In vitro studies have provided several mechanisms for disruption of the epithelial barrier, including activation of different cell-signaling pathways, oxidative stress, and remodeling of the cytoskeleton. Modulation via intestinal microbiota, however, should also be considered. In conclusion, ethanol and its metabolites may act additively or even synergistically in vivo. Therefore, in vivo studies investigating the effects of ethanol and its byproducts on permeability of the small and large intestines are warranted.

The alcohol dehydrogenase 1C(rs698) genotype and breast cancer: a meta-analysis

Published data regarding the association between alcohol dehydrogenase (ADH) 1C genotypes and breast cancer risk show conflicting results. The authors performed this meta-analysis on 1969 patients and 2244 controls from 4 (including 7 study populations) related case-control studies to estimate the association between ADH1C(rs698) genotyping information and breast cancer risk. According to the 6 eligible populations, the odds ratios (ORs) and 95% confidence intervals (CIs) for breast cancer risk for ADH1C (1-2) versus ADH1C (2-2) , ADH1C (1-1) versus ADH1C (2-2) genotype, and ADH1C (1) versus ADH1C (2) were 1.16 (0.95-1.42), 1.17 (0.95-1.44), and 1.05 (0.96-1.16), respectively. The OR (95% CI) for ADH1C (1-1) + ADH1C (1-2) versus ADH1C (2-2) from the 7 study populations was 1.14 (0.96-1.36). Meanwhile, genotypes of ADH1C (1-1) + ADH1C (1-2) increased the risk of breast cancer in drinkers (OR = 1.35; 95% CI = 1.03-1.76). This meta-analysis suggested that the ADH1C (1) allele might modestly influence the effect of alcohol on breast cancer but is not an independent risk factor for breast cancer. However, more restricted prospective studies are needed.

ADH1C Ile350Val polymorphism and cancer risk: evidence from 35 case-control studies

BACKGROUND

Alcohol dehydrogenase 1C (ADH1C) is the key enzyme catalyze oxidation of alcohol to acetaldehyde, which plays vital roles in the etiology of various cancer. To date, studies investigated the association between a functional polymorphism in ADH1C, Ile350Val (rs698), and risk of cancer have shown inclusive results.

METHODS

A meta-analysis based on 35 case-control studies was performed to address this issue. Odds ratios (OR) with 95% confidence intervals (CIs) were used to assess the association. The statistical heterogeneity across studies was examined with χ2-based Q-test.

RESULTS

Overall, no significant associations between ADH1C Ile350Val polymorphism and cancer risk were observed in any genetic models (P>0.05). In the stratified analyses, there was a significantly increased cancer risk among African (Val/Val vs. Ile/Ile OR  =  2.19, 95% CI  =  1.29-3.73, P(heterogeneity)  =  0.989; Ile/Val + Val/Val vs. Ile/Ile: OR  =  1.79, 95%CI  =  1.18-2.71, P(heterogeneity)  =  0.761; Val/Val vs. Ile/Val + Ile/Ile: OR  =  1.92, 95% CI  =  1.16-3.17, P(heterogeneity)  =  0.981) and Asian (Ile/Val vs. Ile/Ile: OR  =  1.58, 95% CI  =  1.32-1.90, P(heterogeneity)  =  0.375; Val/Val vs. Ile/Ile: OR  =  3.84, 95% CI  =  1.74-8.49, P(heterogeneity)  =  0.160; Ile/Val + Val/Val vs. Ile/Ile: OR  =  1.65, 95% CI  =  1.38-1.96, P(heterogeneity)  =  0.330; Val/Val vs. Ile/Val + Ile/Ile: OR  =  3.54, 95% CI  =  1.62-7.75, P(heterogeneity)  =  0.154) studies.

CONCLUSIONS

The results indicate that ADH1C Ile350Val polymorphism may contribute to cancer risk among Africans and Asians. Additional comprehensive system analyses are required to validate this association combined with other related polymorphisms.

Epidemiology and pathophysiology of alcohol and breast cancer: Update 2012

AIMS

To update epidemiological data on alcohol and breast cancer, with special emphasis on light alcohol consumption, and to review mechanisms of alcohol mediated mammary carcinogenesis.

METHODS

For epidemiological data, in November 2011 we performed a literature search in various bibliographic databases, and we conducted a meta-analysis of data on light alcohol drinking. Relevant mechanistic studies were also reviewed to November 2011.

RESULTS

A significant increase of the order of 4% in the risk of breast cancer is already present at intakes of up to one alcoholic drink/day. Heavy alcohol consumption, defined as three or more drinks/day, is associated with an increased risk by 40-50%. This translates into up to 5% of breast cancers attributable to alcohol in northern Europe and North America for a total of approximately 50,000 alcohol-attributable cases of breast cancer worldwide. Up to 1-2% of breast cancers in Europe and North America are attributable to light drinking alone, given its larger prevalence in most female populations when compared with heavy drinking. Alcohol increases estrogen levels, and estrogens may exert its carcinogenic effect on breast tissue either via the ER or directly. Other mechanisms may include acetaldehyde, oxidative stress, epigenetic changes due to a disturbed methyl transfer and decreased retinoic acid concentrations associated with an altered cell cycle.

CONCLUSIONS

Women should not exceed one drink/day, and women at elevated risk for breast cancer should avoid alcohol or consume alcohol occasionally only.

Alcohol, genetics and risk of breast cancer in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial

We tested the hypothesis that genes involved in the alcohol oxidation pathway modify the association between alcohol intake and breast cancer. Subjects were women aged 55-74 at baseline from the screening arm of the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. Incident breast cancers were identified through annual health surveys. Controls were frequency matched to cases by age and year of entry into the trial. A self-administered food frequency questionnaire queried frequency and usual serving size of beer, wine or wine coolers, and liquor. Three SNPs in genes in the alcohol metabolism pathway were genotyped: alcohol dehydrogenase 2, alcohol dehydrogenase 3, and CYP2E1. The study included 1,041 incident breast cancer cases and 1,070 controls. In comparison to non-drinkers, the intake of any alcohol significantly increased the risk of breast cancer, and this risk increased with each category of daily alcohol intake (OR 2.01, 95% CI 1.14, 3.53) for women who drank three or more standard drinks per day. Stratification by genotype revealed significant gene/environment interactions. For the ADH1B gene, there were statistically significant associations between all levels of alcohol intake and risk of breast cancer (all OR > 1.34 and all lower CI > 1.01), while for women with the GA or AA genotype, there were no significant associations between alcohol intake and risk of breast cancer. Alcohol intake, genes involved in alcohol metabolism and their interaction increase the risk of breast cancer in post-menopausal women. This information could be useful for primary care providers to personalize information about breast cancer risk reduction.

Alcohol consumption, alcohol dehydrogenase 1C (ADH1C) genotype, and risk of colorectal cancer in the Netherlands Cohort Study on diet and cancer

Within the Netherlands Cohort Study (1986), we examined associations between alcohol consumption, the alcohol dehydrogenase 1C (ADH1C) genotype, and risk of colorectal cancer (CRC). After a follow-up period of 7.3 years, 594 CRC cases with information on genotype and baseline alcohol intake were available for analyses. Adjusted incidence rate ratios (RRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models. In subjects who reported to have consumed equal amounts of total alcohol both 5 years before baseline and at baseline, drinkers of ≥30g of alcohol per day with the ADH1C*2/*2 genotype were associated-although not statistically significant-with an increased risk of CRC relative to abstainers with the ADH1C*1/*1 genotype (RR: 1.91, 95% CI: 0.68, 5.34). The risk estimate in this exposure group increased slightly when compared with light drinkers of ≥0.5-<5g/day with the ADH1C*1/*1 genotype (RR: 2.32, 95% CI: 0.80, 6.72). The interaction term however, was not statistically significant (P>.05). In subjects who reported to have consumed equal amounts of total alcohol both 5 years before baseline and at baseline, drinkers of ≥30g of alcohol per day were associated-although not statistically significant-with an increased risk of CRC relative to abstainers (RR: 1.38, 95% CI: 0.80, 2.38). This risk estimate for high-level drinkers became stronger when compared with light drinkers (RR: 1.74, 95% CI: 1.01, 2.99). 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. In conclusion, both genotype and alcohol consumption were associated with an increased risk of CRC. Owing to limited statistical power, we found no apparent evidence for the ADH1C genotype as effect modifier of the relationship between alcohol intake and CRC. Nevertheless, the interaction deserves further investigation in larger genetic epidemiologic studies.

Further studies on the potential contribution of acetaldehyde accumulation and oxidative stress in rat mammary tissue in the alcohol drinking promotion of breast cancer

There is available evidence supporting a positive association between alcohol intake and risk of breast cancer. However, there is limited information regarding possible mechanisms for this effect. Past studies from our laboratory suggest that acetaldehyde accumulation in mammary tissue after alcohol intake may be of particular relevance and that cytosolic and microsomal in situ bioactivation of ethanol to acetaldehyde and free radicals and the resulting stimulation of oxidative stress could be a significant early event related to tumor promotion. In the present studies repetitive alcohol drinking for 28 days was found to produce significant decreases in the mammary tissue content of GSH and alpha tocopherol and in glutathione S-transferase or glutathione reductase activities. In contrast, glutathione peroxidase activity was slightly increased. Malondialdehyde determinations did not show the occurrence of lipid peroxidation while the xylenol orange procedure gave positive results. The mammary microsomal metabolism of ethanol to acetaldehyde was not induced after an acute dose of ethanol or acetone able to induce the activity of its liver counterpart. The cytosolic pathway of alcohol metabolism instead was significantly enhanced by these two treatments. No increased generation of comet images was found either in mammary tissue or in liver under the experimental conditions tested. Results suggest that, while acetaldehyde accumulation in mammary tissue could be a critical event resulting from increasing production of acetaldehyde in situ plus an additional amount of it arriving via blood, other factors such as poor handling of the accumulated acetaldehyde could be also relevant.

Inhibition of rat mammary microsomal oxidation of ethanol to acetaldehyde by plant polyphenols

We previously reported that the microsomal fraction from rat mammary tissue is able to oxidize ethanol to acetaldehyde, a mutagenic-carcinogenic metabolite, depending on the presence of NADPH and oxygen but not inhibited by carbon monoxide or other cytochrome P450 inhibitors. The process was strongly inhibited by diphenyleneiodonium, a known inhibitor of NADPH oxidase, and by nordihydroguaiaretic acid, an inhibitor of lipoxygenases. This led us to suggest that both enzymes could be involved. With the purpose of identifying natural compounds present in food with the ability to decrease the production of acetaldehyde in mammary tissue, in the present studies, several plant polyphenols having inhibitory effects on lipoxygenases and of antioxidant nature were tested as potential inhibitors of the rat mammary tissue microsomal pathway of ethanol oxidation. We included in the present screening study 32 polyphenols having ready availability and that were also tested against the rat mammary tissue cytosolic metabolism of ethanol to acetaldehyde. Several polyphenols were also able to inhibit the microsomal ethanol oxidation at concentrations as low was 10-50 μM. The results of these screening experiments suggest the potential of several plant polyphenols to prevent in vivo production and accumulation of acetaldehyde in mammary tissue.

Acetaldehyde as an underestimated risk factor for cancer development: role of genetics in ethanol metabolism. Genes Nutr. 2010;5:121-128. [PMID: 19847467 DOI: 10.1007/s12263-009-0154-1]

Chronic ethanol consumption is a strong risk factor for the development of certain types of cancer including those of the upper aerodigestive tract, the liver, the large intestine and the female breast. Multiple mechanisms are involved in alcohol-mediated carcinogenesis. Among those the action of acetaldehyde (AA), the first metabolite of ethanol oxidation is of particular interest. AA is toxic, mutagenic and carcinogenic in animal experiments. AA binds to DNA and forms carcinogenic adducts. Direct evidence of the role of AA in alcohol-associated carcinogenesis derived from genetic linkage studies in alcoholics. Polymorphisms or mutations of genes coding for AA generation or detoxifying enzymes resulting in elevated AA concentrations are associated with increased cancer risk. Approximately 40% of Japanese, Koreans or Chinese carry the AA dehydrogenase 2*2 (ALDH2*2) allele in its heterozygous form. This allele codes for an ALDH2 enzyme with little activity leading to high AA concentrations after the consumption of even small amounts of alcohol. When individuals with this allele consume ethanol chronically, a significant increased risk for upper alimentary tract and colorectal cancer is noted. In Caucasians, alcohol dehydrogenase 1C*1 (ADH1C*1) allele encodes for an ADH isoenzyme which produces 2.5 times more AA than the corresponding allele ADH1C*2. In studies with moderate to high alcohol intake, ADH1C*1 allele frequency and rate of homozygosity was found to be significantly associated with an increased risk for cancer of the upper aerodigestive tract, the liver, the colon and the female breast. These studies underline the important role of acetaldehyde in ethanol-mediated carcinogenesis.

An empirical comparison of meta-analyses of published gene-disease associations versus consortium analyses

PURPOSE

Consortia of investigators currently compile sufficiently large sample sizes to investigate the effects of low-risk susceptibility genetic variants. It is not clear how the results obtained by consortia compare with those derived from meta-analyses of published studies.

METHODS

We performed meta-analyses of published data for 16 genetic polymorphisms investigated by the Breast Cancer Association Consortium, and compared sample sizes, heterogeneity, and effect sizes. PubMed, Web of Science, and Human Genome Epidemiology Network databases were searched for breast cancer case-control association studies.

RESULTS

We found that meta-analyses of published data and consortium analyses were based on substantially different data. Published data by non-consortium teams amounted on average to 26.9% of all available data (range 3.0 -50.0%). Both approaches showed statistically significant decreased breast cancer risks for CASP8 D302H. The meta-analyses of published data demonstrated statistically significant results for five other genes and the consortium analyses for two other genes, but the strength of this evidence, evaluated on the basis of the Venice criteria, was not strong.

CONCLUSIONS

Because both approaches identified the same gene out of 16 candidates, the methods can be complimentary. The expense and complexity of consortium-based studies should be considered vis-à-vis the potential methodological limitations of synthesis of published studies.

Contribution of alcohol and tobacco use in gastrointestinal cancer development

Tobacco smoke and alcohol are major risk factors for a variety of cancer sites, including those of the gastrointestinal tract. Tobacco smoke contains a great number of mutagenic and carcinogenic compounds, including polycyclic carbohydrates, nitrosamines, and nicotine, while ethanol per se has only weak carcinogenic potential, but its first metabolite, acetaldehyde, is a mutagen and carcinogen, since it forms stable adducts with DNA. The possibility of proto-oncogene mutation in gastrointestinal mucosa cells may be associated with tobacco smoking-induced cancers through the formation of unfavorable DNA adducts. Individuals with defective DNA repair mechanisms and unfavorable genetic make-up for carcinogen metabolism may be at increased risk for gastrointestinal cancers. Individuals with a high production rate of acetaldehyde from ethanol also have an increased cancer risk when they drink chronically. These include individuals with a genetically determined increased acetaldehyde production due to alcohol dehydrogenase polymorphism and those with a decreased detoxification of acetaldehyde due to acetaldehyde dehydrogenase mutation. In addition, oral bacterial overgrowth due to poor oral hygiene also increases salivary acetaldehyde. Dietary deficiencies such as a lack of folate, riboflavine, and zinc may also contribute to the increase cancer risk in the alcoholic patient. It is of considerable importance that smoking and drinking act synergistically. Smoking increases the acetaldehyde burden following alcohol consumption and drinking enhances the activation of various procarcinogens present in tobacco smoke due to increased metabolic activation by an induced cytochrome P450-2E1-dependent microsomal biotransformation system in the mucosa of the upper digestive tract and the liver.

Acetaldehyde accumulation in rat mammary tissue after an acute treatment with alcohol

Previous studies reported the presence in rat mammary tissue of a cytosolic xanthine oxidoreductase pathway for the metabolism of alcohol to acetaldehyde and hydroxyl radicals and to the microsomal biotransformation of ethanol to acetaldehyde. It was also reported that after chronic ethanol drinking stressful oxidative conditions can be observed. The present work reports that even after single doses of ethanol, given at three different levels (6.3 g kg(-1); 3.8 g kg(-1) or 0.6 g kg(-1) p.o.), acetaldehyde accumulates for prolonged periods of time in the mammary tissue to reach concentrations higher than in blood (e.g. 5.1+/-1.2 nmol g(-1) versus 0.2+/-0.1 nmol ml(-1), for 6.3 g kg(-1) dose, 6 h after intoxication). The presence in rat mammary tissue of low activities of additional enzymes able to generate acetaldehyde was established (alcohol dehydrogenase: 0.97+/-0.84 mU mg(-1) protein; CYP2E1: 1.30+/-0.12 x 10(-2) pmol 4-nitrocatechol min(-1) mg(-1) protein) and a low activity of aldehyde dehydrogenase was observed in the cytosolic, mitochondrial and microsomal fractions (0.02+/-0.04; 0.35+/-0.09 and 0.72+/-0.19 mU mg(-1) protein, respectively). After a single high dose of ethanol, an increased susceptibility to oxidative stress was observed, as evidenced by changes in the shape of t-butylhydroperoxide induced emission of chemiluminescence in mammary tissue (6.3 g kg(-1) dose; at 3 and 6 h). In summary, the results show that even after single doses of ethanol, acetaldehyde, either formed in situ or arriving via blood, tends to accumulate in mammary tissue and that this condition might decrease cell defenses against injury.

Molecular mechanisms of alcohol-mediated carcinogenesis

Approximately 3.6% of cancers worldwide derive from chronic alcohol drinking, including those of the upper aerodigestive tract, the liver, the colorectum and the breast. Although the mechanisms for alcohol-associated carcinogenesis are not completely understood, most recent research has focused on acetaldehyde, the first and most toxic ethanol metabolite, as a cancer-causing agent. Ethanol may also stimulate carcinogenesis by inhibiting DNA methylation and by interacting with retinoid metabolism. Alcohol-related carcinogenesis may interact with other factors such as smoking, diet and comorbidities, and depends on genetic susceptibility.

Overview of the role of alcohol dehydrogenase and aldehyde dehydrogenase and their variants in the genesis of alcohol-related pathology

Alcohol dehydrogenase (ADH) and mitochondrial aldehyde dehydrogenase (ALDH2) are responsible for metabolizing the bulk of ethanol consumed as part of the diet and their activities contribute to the rate of ethanol elimination from the blood. They are expressed at highest levels in liver, but at lower levels in many tissues. This pathway probably evolved as a detoxification mechanism for environmental alcohols. However, with the consumption of large amounts of ethanol, the oxidation of ethanol can become a major energy source and, particularly in the liver, interferes with the metabolism of other nutrients. Polymorphic variants of the genes for these enzymes encode enzymes with altered kinetic properties. The pathophysiological effects of these variants may be mediated by accumulation of acetaldehyde; high-activity ADH variants are predicted to increase the rate of acetaldehyde generation, while the low-activity ALDH2 variant is associated with an inability to metabolize this compound. The effects of acetaldehyde may be expressed either in the cells generating it, or by delivery of acetaldehyde to various tissues by the bloodstream or even saliva. Inheritance of the high-activity ADH β2, encoded by theADH2*2gene, and the inactiveALDH2*2gene product have been conclusively associated with reduced risk of alcoholism. This association is influenced by gene–environment interactions, such as religion and national origin. The variants have also been studied for association with alcoholic liver disease, cancer, fetal alcohol syndrome, CVD, gout, asthma and clearance of xenobiotics. The strongest correlations found to date have been those between theALDH2*2allele and cancers of the oro-pharynx and oesophagus. It will be important to replicate other interesting associations between these variants and other cancers and heart disease, and to determine the biochemical mechanisms underlying the associations.

Alcohol dehydrogenase genetic polymorphisms, low-to-moderate alcohol consumption, and risk of breast cancer

BACKGROUND

In vitro, human isoenzymes encoded by genes homozygous for the ADH1C*1 or ADH1B*2 alleles metabolize ethanol to acetaldehyde at a faster rate than those homozygous for the ADH1C*2 or ADH1B*1 allele. Because alcohol is a known risk factor for breast cancer, we evaluated the joint association of genetic variants in ADH and alcohol consumption in relation to breast cancer.

METHODS

A nested case-control study of 321 cases and matched controls was conducted. Five single nucleotide polymorphisms (SNPs) in the ADH1C and ADH1B genes were genotyped. Logistic regression was used to assess odds ratios (ORs) and 95% confidence limits (CIs) for each SNP. Haplotype analysis of all 5 SNPs was also undertaken.

RESULTS

Among drinkers, the median intake of total alcohol was 13 g/wk (10th-90th percentiles; 4.5-135.9) in cases and 18 g/wk (10th-90th percentiles; 4.5-104.1) in controls. Women who drank alcohol tended to be at an increased risk of developing breast cancer compared with those who did not drink (OR=1.40%, 95% CI 0.97-2.03), particularly those who were premenopausal at the time of breast cancer diagnosis (OR=2.69%, 95% CI: 1.00-7.26). Of the known functional alleles, breast cancer risk was not significantly increased among carriers of at least 1 ADH1C*1 or ADH1B*2 allele, when compared with those homozygous for the genotype at each locus. However, breast cancer risk tended to be lower among women who inherited the G allele at ADH1B IVS1+896A>G (OR=0.62, 95% CI 0.37-1.04). Overall haplotype frequencies were not significantly different between cases and controls.

CONCLUSIONS

In this study low levels of alcohol are associated with a modest increase in breast cancer risk that is not altered by known functional allelic variants of the ADH1B and 1C gene. The protective association conferred by the G allele at ADH1B IVS1+896A>G needs further evaluation.

Alcohol metabolism, alcohol intake, and breast cancer risk: a sister-set analysis using the Breast Cancer Family Registry

Moderate alcohol intake has been consistently associated with a modest (30-50%) increase in breast cancer risk, but it remains unclear if certain individuals have higher susceptibility to the harmful effects of alcohol intake. Individuals differ in their ability to metabolize alcohol through genetic differences in alcohol dehydrogenase (ADH), the enzyme that catalyzes the oxidation of approximately 80% of ethanol to acetaldehyde, a known carcinogen. Using data from the Breast Cancer Family Registry (n = 811 sister sets), we examined whether sisters with breast cancer differ with respect to alcohol consumption and alcohol metabolism (measured by polymorphisms in ADH1B and ADH1C) compared to their sisters without breast cancer. Neither alcohol drinking nor alcohol metabolizing ADH1B and ADH1C genotypes were associated with breast cancer risk. However, only 19% and 42% of sisters were discordant by ADH1B and ADH1C, respectively, and even fewer were discordant by both genotype and alcohol intake, making it difficult to detect differences if they existed.

Alcohol dehydrogenase 3, glutathione S-transferase M1 and T1 polymorphisms, alcohol consumption and hepatocellular carcinoma (Italy)

OBJECTIVE

The aim of this study was to investigate the role of alcohol dehydrogenase type 3 (ADH3), glutathione S-transferase M1 (GSTM1) and T1 (GSTT1) polymorphisms in modifying hepatocellular carcinoma (HCC) risk according to alcohol intake.

METHODS

A hospital-based case-control study was conducted in two areas of North Italy. Two-hundred cases hospitalized for HCC and 400 controls were recruited. Genotypes were determined using PCR and the PCR/restriction fragment length polymorphism-based method.

RESULTS

There was no association of the putative risk genotypes ADH3(1-1), GSTM1 null and GSTT1 null with HCC (odds ratio [OR], 0.8; 95% confidence interval [CI], 0.5-1.3; OR, 1.0; 95% CI, 0.6-1.5; OR, 0.8; 95% CI, 0.4-1.4, respectively). A steady increase in HCC risk with increasing alcohol intake, which did not vary according to ADH3 and GSTT1 genotypes, was observed. Nevertheless, the OR for HCC due to an alcohol intake of >100 g of ethanol per day increased in subjects with GSTM1 null genotype (OR, 8.5; 95% CI, 3.9-18.6) compared to GSTM1 non-null genotype (OR, 4.5; 95% CI, 2.0-10.0).

CONCLUSIONS

ADH3(1-1) and GSTT1 null genotypes did not modify the risk of HCC due to alcohol intake whereas an influence of GSTM1 null genotype for high ethanol consumption was suggested.

National Institute on Alcohol Abuse and Alcoholism Report on Moderate Drinking

In support of the 2005 update of the U.S. Department of Agriculture/U.S. Department of Health and Human Services Dietary Guidelines, the National Institute on Alcohol Abuse and Alcoholism was asked to assess the strength of the evidence related to health risks and potential benefits of moderate alcohol consumption, with particular focus on the areas of cardiovascular disease, breast cancer, obesity, birth defects, breastfeeding, and aging. The findings were reviewed by external researchers with extensive research backgrounds on the consequences and benefits of alcohol consumption. This report now serves as the National Institutes of Health's formal position paper on the health risks and potential benefits of moderate alcohol use.

Ethanol-induced oxidative stress and acetaldehyde formation in rat mammary tissue: potential factors involved in alcohol drinking promotion of breast cancer

Recent studies from our laboratory provided evidence that part of the carcinogenic effects of ethanol consumption might be related to its in situ metabolism at cytosolic and microsomal levels, to the mutagen acetaldehyde and to hydroxyl and 1-hydroxyethyl radicals. In this work, we report on our experiments where Sprague-Dawley female rats were exposed to the standard Lieber & De Carli diet for 28 days. We observed: the induction of the (xanthineoxidoreductase mediated) cytosolic and microsomal (lipoxygenase mediated) pathways of ethanol metabolism; promotion of oxidative stress as shown by increased formation of lipid hydroperoxides; delay in the t-butylhydroperoxide induced chemiluminiscence, and a significant decrease in protein sulfhydryls. In addition, the epithelial cells showed ultrastructural alterations consisting of markedly irregular nuclei, with frequent invaginations at the level of the nuclear envelope, condensation of chromatin around the inner nuclear membrane, and marked dilatation of the nuclear pores showing filamentous material exiting to the cytoplasm. In conclusion, the presence in mammary epithelial cells of cytosolic and microsomal pathways of ethanol bioactivation to carcinogenic and to tumorigenic metabolites might play a role in alcohol promotion of breast cancer.

ADH3 genotype, alcohol intake and breast cancer risk

Moderate alcohol consumption of approximately 1-2 drinks per day has been associated with a 30-50% increase in breast cancer risk. Individuals differ in their ability to metabolize alcohol through genetic differences in alcohol dehydrogenase (ADH), the enzyme that catalyzes the oxidation of approximately 80% of ethanol to acetaldehyde, a known carcinogen. Individuals differ in their ADH genotype, and one locus in particular (ADH3) is polymorphic in Caucasian populations. Using data from the Long Island Breast Cancer Study Project, we examined whether fast metabolizers of alcohol, as measured by the ADH3(1-1) genotype, have a higher risk of breast cancer from alcohol intake compared with those individuals who are slow metabolizers, but consume similar amounts of alcohol. We combined genotyping information with questionnaire data on 1047 breast cancer cases and 1101 controls and used unconditional logistic regression methods to estimate multivariate-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) between alcohol intake and breast cancer risk. Among individuals homozygous for the fast metabolizing allele (ADH(3)1-1), a lifetime alcohol consumption of 15-30 g/day (approximately 1-2 drinks per day) increased breast cancer risk by 2-fold (OR=2.0, 95% CI=1.1-3.5). In contrast, the increase in risk from a lifetime alcohol consumption of 15-30 g/day was less pronounced in the intermediate and slow metabolizing groups, respectively: ADH3(1-2) (OR=1.5, 95% CI 0.9-2.4) and ADH(3)2-2 (OR=1.3, 95% CI 0.5-3.5). Fast metabolizers who drank 15-30 g/day of alcohol had 2.3 times (95% CI 1.3-4.0) greater risk of breast cancer than non-drinkers who were intermediate or slow metabolizers. This association for fast metabolizers who drank 15-30 g/day was particularly pronounced among premenopausal women (premenopausal women OR=2.9, 95 % CI=1.2-7.1; postmenopausal women OR=1.8, 95% CI=0.9-3.8). These population-based data support the hypothesis that fast metabolizers of alcohol have a higher risk of breast cancer risk, from alcohol intake than slow metabolizers.

Interaction between the ADH1C polymorphism and maternal alcohol intake in the risk of nonsyndromic oral clefts: an evaluation of the contribution of child and maternal genotypes

BACKGROUND

Maternal alcohol consumption has been associated with an increased risk of nonsyndromic oral clefts in some studies. Study of gene-environment interaction may provide insight into the reasons for their discrepancies observed. We focused on a polymorphism of the ADH1C gene (third gene of the class I alcohol dehydrogenase family), involved in the metabolism of ethanol and other alcohols.

METHODS

Data come from a French case-control study (1998-2001), which tested the association between maternal alcohol consumption during the first trimester of pregnancy and the risk of nonsyndromic oral clefts (240 cases, 236 controls). A case-parent study design looked at the association with an ADH1C polymorphism (Ile349Val site) and potential gene-environment interaction effects. A log-linear model was used to distinguish the direct effect of the child's genotype from the maternally mediated effects.

RESULTS

An increased risk of nonsyndromic oral clefts was observed for women who reported drinking alcohol during the first trimester, compared with women who did not. The mutated ADH1C allele carried by the child seemed to have a protective effect against the risk of oral clefts (RRone copy, 0.71; 95% confidence interval [CI], 0.50-1.02; RRtwo copies, 0.63; 95% CI, 0.3-1.3). The maternal genotype played a less important role than the child's, and its action remains unclear. No significant evidence of interaction effects between the ADH1C genotype and maternal alcohol consumption was observed.

CONCLUSIONS

Because the ADH1C gene is involved in the metabolic pathways of many alcohols, we propose several hypotheses about the causal pathway, including ethanol oxidation activity and, more probably, retinol oxidation.

Understanding breast cancer risk -- where do we stand in 2005?

Breast cancer is the most frequent cancer in women and represents the second leading cause of cancer death among women (after lung cancer). The etiology of breast cancer is still poorly understood with known breast cancer risk factors explaining only a small proportion of cases. Risk factors that modulate the development of breast cancer discussed in this review include: age, geographic location (country of origin) and socioeconomic status, reproductive events, exogenous hormones, lifestyle risk factors (alcohol, diet, obesity and physical activity), familial history of breast cancer, mammographic density, history of benign breast disease, ionizing radiation, bone density, height, IGF- 1 and prolactin levels, chemopreventive agents. Additionally, we summarized breast cancer risk associated with the following genetic factors: breast cancer susceptibility high-penetrance genes (BRCA1, BRCA2, p53, PTEN, ATM, NBS1 or LKB1) and low-penetrance genes such as cytochrome P450 genes (CYP1A1, CYP2D6, CYP19), glutathione S-transferase family (GSTM1, GSTP1), alcohol and one-carbon metabolism genes (ADH1C and MTHFR), DNA repair genes (XRCC1, XRCC3, ERCC4/XPF) and genes encoding cell signaling molecules (PR, ER, TNFalpha or HSP70). All these factors contribute to a better understanding of breast cancer risk. Nonetheless, in order to evaluate more accurately the overall risk of breast tumorigenesis, novel genetic and phenotypic traits need to be identified.

The etiology of alcohol-induced breast cancer

Breast cancer is the most common cancer in women in the United States, and it is second among cancer deaths in women. Results of most epidemiologic studies, as well as of most experimental studies in animals, have shown that alcohol intake is associated with increased breast cancer risk. Alcohol consumption may cause breast cancer through different mechanisms, including through mutagenesis by acetaldehyde, through perturbation of estrogen metabolism and response, and by inducing oxidative damage and/or by affecting folate and one-carbon metabolism pathways. Alcohol-metabolizing enzymes are present in human breast tissue. Acetaldehyde is a known, although weak, mutagen. However, results of some studies with human subjects implicate this agent in the context of genetic susceptibilities to increased ethanol metabolism. Reactive oxygen species, resulting from ethanol metabolism, may be involved in breast carcinogenesis by causing damage, as well as by generating DNA and protein adducts. Alcohol interferes with estrogen pathways in multiple ways, influencing hormone levels and effects on the estrogen receptors. With regard to one-carbon metabolism, alcohol can negatively affect folate levels, and the folate perturbation affects DNA methylation and DNA synthesis, which is important in carcinogenesis. Some study results indicate that genetic variants of one-carbon metabolism genes might increase alcohol-related breast cancer risk. For all these pathways, genetic polymorphisms might play a role in increasing further a woman's risk for breast cancer. Additional studies are needed to determine the relative importance of these pathways, as well as the modifying influence by genetic variation.

Alcohol and public health

Alcoholic beverages, and the problems they engender, have been familiar fixtures in human societies since the beginning of recorded history. We review advances in alcohol science in terms of three topics: the epidemiology of alcohol's role in health and illness; the treatment of alcohol use disorders in a public health perspective; and policy research and options. Research has contributed substantially to our understanding of the relation of drinking to specific disorders, and has shown that the relation between alcohol consumption and health outcomes is complex and multidimensional. Alcohol is causally related to more than 60 different medical conditions. Overall, 4% of the global burden of disease is attributable to alcohol, which accounts for about as much death and disability globally as tobacco and hypertension. Treatment research shows that early intervention in primary care is feasible and effective, and a variety of behavioural and pharmacological interventions are available to treat alcohol dependence. This evidence suggests that treatment of alcohol-related problems should be incorporated into a public health response to alcohol problems. Additionally, evidence-based preventive measures are available at both the individual and population levels, with alcohol taxes, restrictions on alcohol availability, and drinking-driving countermeasures among the most effective policy options. Despite the scientific advances, alcohol problems continue to present a major challenge to medicine and public health, in part because population-based public health approaches have been neglected in favour of approaches oriented to the individual that tend to be more palliative than preventative.

Prospective study of alcohol consumption and breast cancer risk in Japanese women

Epidemiologic evidence is lacking for the association between alcohol consumption and the risk of breast cancer in Japanese women. We addressed this association in a prospective cohort study with an average follow-up of 7.6 years. At baseline (1988-1990), cohort participants completed a self-administered questionnaire that included alcohol use, reproductive history and hormone use. The women were followed up for breast cancer incidence through December 31, 1997. Cox proportional hazards models were used to calculate relative risks (RRs) and 95% confidence intervals (CIs) for breast cancer incidence and any association with alcohol consumption. During a follow-up of 271,412 person-years, we identified 151 women with breast cancer, of whom 45 were current drinkers and 11 drank > or =15 g of alcohol/day. After adjustment for age and other potential risk factors for breast cancer, the RR for current drinkers was 1.27 (95% CI 0.87-1.84) compared to nondrinkers. Average alcohol intake of <15 g/day did not significantly increase the risk for breast cancer. However, risk was significantly increased for women who consumed > or =15 g/day of alcohol (RR = 2.93, 95% CI 1.55-5.54). Age at starting drinking and frequency of consumption per week were not significantly associated with breast cancer risk. Our cohort study demonstrated that Japanese women who consume at least a moderate amount of alcohol have an increased risk of breast cancer.

Lung cancer in humans is not associated with lifetime total alcohol consumption or with genetic variation in alcohol dehydrogenase 3 (ADH3)

Although there is clear evidence that smoking is the primary risk factor for lung cancer, not all variation in disease risk is understood. There is some evidence that alcohol may contribute to risk. We examined lifetime and recent (12-24 mo previous) alcohol consumption in relation to risk of lung cancer in a case-control study in western New York. In addition we examined the alcohol dehydrogenase 3 (ADH3) genotype in relation to lung cancer risk; ADH3 is rate limiting in alcohol metabolism and has a functional polymorphism. We interviewed incident, primary, histologically confirmed lung cancer cases (n = 111) in two counties. Controls were randomly selected from among those residing in the counties, frequency-matched to cases for age and race (n = 1546). Lifetime and recent total alcohol and beverage-specific alcohol consumption as well as relevant confounders were assessed by interview. ADH3 genotype was evaluated by a PCR-restriction fragment length polymorphism assay. Because of the small sample size, power was limited and CI were wide. Residual confounding by smoking remains a concern. Although we found a significant trend for increased risk for beer consumption in the recent period (odds ratio 1.67, 95% CI 0.96-2.92, P for trend = 0.05), chance cannot be ruled out as an explanation. We found no evidence of risk related to lifetime alcohol consumption nor evidence that alcohol dehydrogenase genotype modifies risk related to alcohol and lung cancer.

Sex differences in the toxicokinetics of inhaled solvent vapors in humans 2. 2-propanol

The aim of this study was to evaluate possible sex differences in the inhalation toxicokinetics of 2-propanol vapor. Nine women and eight men were exposed on different occasions for 2 h during light physical exercise (50 W) to 2-propanol (350 mg/m3) and to clean air (control exposure). The level corresponds to the Swedish occupational exposure limit. 2-Propanol and its metabolite acetone were monitored up to 24 h after exposure in exhaled air, blood, saliva, and urine by headspace gas chromatography. Body fat and lean body mass were estimated from sex-specific equations using bioelectrical impedance, body weight, height, and age. Genotypes were determined by PCR-based assays for alcohol dehydrogenase and cytochrome P450 2E1 (CYP2E1). The CYP2E1 phenotype was assessed by the 2-h plasma 6-hydroxychlorzoxazone/chlorzoxazone metabolic ratio in vivo. The toxicokinetic profile in blood was analyzed using a one-compartment population model. The following sex differences were significant at the p = 0.05 level (Student's t test). The respiratory uptake was lower and the volume of distribution smaller in females. The women had a slightly shorter half-time of 2-propanol in blood and a higher apparent total clearance when corrected for body composition. However, women reached approximately four times higher 2-propanol levels in exhaled air at 10-min postexposure and onward. Acetone in blood was markedly higher in females than in males in the control experiment and slightly higher following exposure to 2-propanol. A marked sex difference was that of a 10-fold higher in vivo blood:breath ratio in men, suggesting sex differences in the lung metabolism of 2-propanol. The most marked sex difference was that of salivary acetone, for which an approximately 100-fold increase was seen in women, but no increase in men, after exposure to 2-propanol compared to clean air. The toxicokinetic analysis revealed no significant differences in toxicokinetics between subjects of different metabolic genotypes or phenotypes. In conclusion, the study indicates several sex differences in the inhalation toxicokinetics of 2-propanol. Most of these differences are consistent with anatomical differences between women and men. However, body build can not explain the sex differences in 2-propanol levels in expired air and acetone in saliva.

Interaction between alcohol dehydrogenase II gene, alcohol consumption, and risk for breast cancer

MaeIII Restriction Fragment Length Polymorphism in exon 3 of the alcohol dehydrogenase II was assessed in serum from 467 randomly selected German women and 278 women with invasive breast cancer to evaluate the interaction between a polymorphism of the alcohol dehydrogenase II gene, alcohol consumption and risk for breast cancer. In both groups, usual consumption of different alcoholic beverages was asked for using semiquantitative food frequency questionnaires. We used multivariable logistic regression to separately estimate the association between alcohol consumption and alcohol dehydrogenase II polymorphism in the population sample and women with breast cancer. The alcohol dehydrogenase II polymorphism was detected in 14 women from the population sample (3.0%) and in 27 women with invasive breast cancer (9.7%). Frequency of alcohol consumption was independent of the genotype in the population sample. In women with breast cancer, there was a significant inverse association between the alcohol dehydrogenase II polymorphism and frequency of alcohol consumption (adjusted case-only odds ratio over increasing frequency of alcohol consumption=0.5; P for interaction=0.02). We observed a gene-environment interaction between the alcohol dehydrogenase II polymorphism, alcohol consumption, and risk for breast cancer. Breast cancer risk associated with alcohol consumption may vary according to the alcohol dehydrogenase II polymorphism, probably due to differences in alcohol metabolism.

Interaction between a single nucleotide polymorphism in the alcohol dehydrogenase 3 gene, alcohol consumption and oral cancer risk

We investigated effects on oral cancer (OC) risk of an interaction between a single nucleotide polymorphism (SNP) in the alcohol dehydrogenase 3 (ADH3) gene and alcohol consumption levels using a hospital-based study of 93 cases and 99 controls conducted in Athens, Greece. This SNP affects ethanol metabolism in vitro and appeared to interact with alcohol consumption in a previous OC study. We also evaluated a SNP in CYP2E1, another gene involved in ethanol metabolism, reported to be associated with OC risk in a European population. Data on genotypes and risk factors obtained from interviews were analyzed using multivariate logistic regression, accounting for potential confounders. No overall (marginal) association was found between OC risk and ADH3 genotypes. An interaction between ADH3 genotypes and alcohol consumption levels, however, was suggested. In non-drinkers, the ADH3(1-1) genotype has higher risk than ADH3(1-2) or ADH3(2-2) genotypes, but for subjects consuming alcohol, lower risk was observed for ADH3. We fit a logistic regression model to estimate the increase in OC risk associated with each alcohol drink consumed per week. We estimated that OC risk increased by 31.5% per drink/week for the ADH3(2-2) genotype, 4.1% for the ADH3(1-2) genotype and 1.6% for the ADH3(1-1) genotype. Evidence of genotype-environment interaction was suggestive (p = 0.048, Wald chi p = 0.145, likelihood ratio). This finding is opposite to that reported for a population in Puerto Rico, where the ADH3(1-1) genotype seemed more sensitive to ethanol exposure. In Greece, genetic variation at the CYP2E1 SNP is almost entirely absent, with only 1 case and 1 control heterozygous for the variant. By contrast, in a population in France where an OC association was reported, the frequency of CYP2E1 heterozygotes was 5% in controls and 9% in OC cases. These findings illustrate the importance of replicating SNP associations both within and between different racial and ethnic groups and geographic regions.

The role of acetaldehyde in the actions of alcohol (update 2000)

BACKGROUND

Recent advances in the field of acetaldehyde (AcH) research have raised the need for a comprehensive review on the role of AcH in the actions of alcohol. This update is an attempt to summarize the available AcH research.

METHODS

The descriptive part of this article covers not only recent research but also the development of the field. Special emphasis is placed on mechanistic analyses, new hypotheses, and conclusions.

RESULTS

Elevated AcH during alcohol intoxication causes alcohol sensitivity, which involves vasodilation associated with increased skin temperature, subjective feelings of hotness and facial flushing, increased heart and respiration rate, lowered blood pressure, sensation of dry mouth or throat associated with bronchoconstriction and allergy reactions, nausea and headache, and also reinforcing reactions like euphoria. These effects seem to involve catecholamine, opiate peptide, prostaglandin, histamine, and/or kinin mechanisms. The contribution of AcH to the pathological consequences of chronic alcohol intake is well established for different forms of cancer in the digestive tract and the upper airways. AcH seems to play a role in the etiology of liver cirrhosis. AcH may have a role in other pathological developments, which include brain damage, cardiomyopathy, pancreatitis, and fetal alcohol syndrome. AcH creates both unpleasant aversive reactions that protect against excessive alcohol drinking and euphoric sensations that may reinforce alcohol drinking. The protective effect of AcH may be used in future treatments that involve gene therapy with or without liver transplantation.

CONCLUSIONS

AcH plays a role in most of the actions of alcohol. The individual variability in these AcH-mediated actions will depend on the genetic polymorphism, not only for the alcohol and AcH-metabolizing enzymes but also for the target sites for AcH actions. The subtle balance between aversive and reinforcing, protecting and promoting factors will determine the overall behavioral and pathological developments.

Investigation of an interaction of alcohol intake and family history on breast cancer risk in the Minnesota Breast Cancer Family Study

BACKGROUND

One explanation for the variability in results in studies of alcohol consumption and breast cancer could be the presence of effect modifiers, such as genetic susceptibility. The authors examined the interaction of alcohol and family history of breast cancer on breast cancer risk in a population-based family study of 426 multigenerational breast cancer families. The authors evaluated whether alcohol use was a stronger risk factor for breast cancer among sisters, daughters, nieces, and granddaughters of breast cancer probands than among women who married into these families.

METHODS

Analyses were performed on surrogate and self-reported data combined and on self-reported data alone. To evaluate the interaction of alcohol and breast cancer risk among women with a family history of breast cancer, the authors performed analyses on all 426 families and on a subset of 132 families that had 3 or more breast and/or ovarian cancers in their family.

RESULTS

A total of 9032 blood relatives and marry-ins and 558 breast cancer cases were available for analysis. In the entire 426 families, there was a suggestion of an interaction of relationship to the proband and frequency of alcohol consumption on breast cancer risk (P(interaction) = 0.14) for surrogate and self-reported information combined. Among first-degree relatives of the proband, daily drinkers had a significantly increased risk of breast cancer compared with never drinkers (RR = 2.45 [1.20, 5.02]), but this increase was less evident among second-degree relatives who reported daily alcohol intake (RR = 1.27 [0.73, 2.22]) and was not evident in marry-ins who reported daily use of alcohol (RR = 0.90 [0.42, 1.90]). The findings based on the subset of 132 high-risk families with 3 or more breast and/or ovarian cancers were similar to findings based on all 426 families (P(interaction) = 0.07). An interaction of family history with alcohol use was also suggested when the analyses were restricted to self-respondents, although the interaction test P-value was no longer of borderline significance.

CONCLUSION

An increased risk of breast cancer due to an increased frequency of alcohol consumption may be limited to women with a family history of breast cancer.

Investigation of an interaction of alcohol intake and family history on breast cancer risk in the Minnesota Breast Cancer Family Study

BACKGROUND

One explanation for the variability in results in studies of alcohol consumption and breast cancer could be the presence of effect modifiers, such as genetic susceptibility. The authors examined the interaction of alcohol and family history of breast cancer on breast cancer risk in a population-based family study of 426 multigenerational breast cancer families. The authors evaluated whether alcohol use was a stronger risk factor for breast cancer among sisters, daughters, nieces, and granddaughters of breast cancer probands than among women who married into these families.

METHODS

Analyses were performed on surrogate and self-reported data combined and on self-reported data alone. To evaluate the interaction of alcohol and breast cancer risk among women with a family history of breast cancer, the authors performed analyses on all 426 families and on a subset of 132 families that had 3 or more breast and/or ovarian cancers in their family.

RESULTS

A total of 9032 blood relatives and marry-ins and 558 breast cancer cases were available for analysis. In the entire 426 families, there was a suggestion of an interaction of relationship to the proband and frequency of alcohol consumption on breast cancer risk (P(interaction) = 0.14) for surrogate and self-reported information combined. Among first-degree relatives of the proband, daily drinkers had a significantly increased risk of breast cancer compared with never drinkers (RR = 2.45 [1.20, 5.02]), but this increase was less evident among second-degree relatives who reported daily alcohol intake (RR = 1.27 [0.73, 2.22]) and was not evident in marry-ins who reported daily use of alcohol (RR = 0.90 [0.42, 1.90]). The findings based on the subset of 132 high-risk families with 3 or more breast and/or ovarian cancers were similar to findings based on all 426 families (P(interaction) = 0.07). An interaction of family history with alcohol use was also suggested when the analyses were restricted to self-respondents, although the interaction test P-value was no longer of borderline significance.

CONCLUSION

An increased risk of breast cancer due to an increased frequency of alcohol consumption may be limited to women with a family history of breast cancer.

Diet and cancer prevention

Research from several sources provides strong evidence that vegetables, fruits, and whole grains, dietary fibre, certain micronutrients, some fatty acids and physical activity protect against some cancers. In contrast, other factors, such as obesity, alcohol, some fatty acids and food preparation methods may increase risks. Unravelling the multitude of plausible mechanisms for the effects of dietary factors on cancer risk will likely necessitate that nutrition research moves beyond traditional epidemiological and metabolic studies. Nutritional sciences must build on recent advances in molecular biology and genetics to move the discipline from being largely 'observational' to focusing on 'cause and effect'. Such basic research is fundamental to cancer prevention strategies that incorporate effective dietary interventions for target populations.

The role of acetaldehyde in the actions of alcohol (update 2000)

BACKGROUND

Recent advances in the field of acetaldehyde (AcH) research have raised the need for a comprehensive review on the role of AcH in the actions of alcohol. This update is an attempt to summarize the available AcH research.

METHODS

The descriptive part of this article covers not only recent research but also the development of the field. Special emphasis is placed on mechanistic analyses, new hypotheses, and conclusions.

RESULTS

Elevated AcH during alcohol intoxication causes alcohol sensitivity, which involves vasodilation associated with increased skin temperature, subjective feelings of hotness and facial flushing, increased heart and respiration rate, lowered blood pressure, sensation of dry mouth or throat associated with bronchoconstriction and allergy reactions, nausea and headache, and also reinforcing reactions like euphoria. These effects seem to involve catecholamine, opiate peptide, prostaglandin, histamine, and/or kinin mechanisms. The contribution of AcH to the pathological consequences of chronic alcohol intake is well established for different forms of cancer in the digestive tract and the upper airways. AcH seems to play a role in the etiology of liver cirrhosis. AcH may have a role in other pathological developments, which include brain damage, cardiomyopathy, pancreatitis, and fetal alcohol syndrome. AcH creates both unpleasant aversive reactions that protect against excessive alcohol drinking and euphoric sensations that may reinforce alcohol drinking. The protective effect of AcH may be used in future treatments that involve gene therapy with or without liver transplantation.

CONCLUSIONS

AcH plays a role in most of the actions of alcohol. The individual variability in these AcH-mediated actions will depend on the genetic polymorphism, not only for the alcohol and AcH-metabolizing enzymes but also for the target sites for AcH actions. The subtle balance between aversive and reinforcing, protecting and promoting factors will determine the overall behavioral and pathological developments.

Genetic polymorphism of alcohol dehydrogenase in europeans: the ADH2*2 allele decreases the risk for alcoholism and is associated with ADH3*1

Polymorphism at the ADH2 and ADH3 loci of alcohol dehydrogenase (ADH) has been shown to have an effect on the predisposition to alcoholism in Asian individuals. However, the results are not conclusive for white individuals. We have analyzed the ADH genotype of 876 white individuals from Spain (n = 251), France (n = 160), Germany (n = 184), Sweden (n = 88), and Poland (n = 193). Peripheral blood samples from healthy controls and groups of patients with viral cirrhosis and alcohol-induced cirrhosis, as well as alcoholics with no liver disease, were collected on filter paper. Genotyping of the ADH2 and ADH3 loci was performed using polymerase chain reaction-restriction fragment length polymorphism methods on white cell DNA. In healthy controls, ADH2*2 frequencies ranged from 0% (France) to 5.4% (Spain), whereas ADH3*1 frequencies ranged from 47. 6% (Germany) to 62.5% (Sweden). Statistically significant differences were not found, however, between controls from different countries, nor between patients with alcoholism and/or liver disease. When all individuals were grouped in nonalcoholics (n = 451) and alcoholics (n = 425), ADH2*2 frequency was higher in nonalcoholics (3.8%) than in alcoholics (1.3%) (P =.0016), whereas the ADH3 alleles did not show differences. Linkage disequilibrium was found between ADH2 and ADH3, resulting in an association of the alleles ADH2*2 and ADH3*1, both coding for the most active enzymatic forms. In conclusion, the ADH2*2 allele decreases the risk for alcoholism, whereas the ADH2*2 and ADH3*1 alleles are found to be associated in the European population.