Genetic polymorphisms of tobacco- and alcohol-related metabolizing enzymes and human esophageal squamous cell carcinoma susceptibility

Clinical features of superficial esophagus squamous cell carcinoma according to alcohol-degrading enzyme ADH1B and ALDH2 genotypes

BACKGROUND

Inactivated alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) are related to esophageal carcinogenesis. We aimed to clarify the clinical features associated with the alcohol-degrading enzyme genotypes, ADH1B and ALDH2. We also investigated the risk factors for metachronous esophageal squamous cell carcinoma (ESCC) and head and neck SCC (HNSCC).

METHODS

We conducted a single-center, retrospective study including patients with ESCC treated by endoscopic resection. Patients were recruited between October 2020 and September 2021. Buccal mucosal swabs were obtained from them to analyze the genetic polymorphisms affecting ADH (ADH1B) and ALDH (ALDH2) activity. Patients were categorized into three groups: both inactivated = double-inactivated group; inactivated ADH1B or ALDH2 = single-inactivated group; and both activated = activated group.

RESULTS

Among the 297 enrolled patients, patients in the double-inactivated group were significantly younger (P < 0.001) and 60% of them were ≤ 50 years old. This group also had more ESCCs located in the upper esophagus (P < 0.001) and more simultaneous multiple ESCCs (P = 0.044). More than half of the patients had multiple Lugol-voiding lesions (LVLs) (P < 0.001) and heavy alcohol consumers (P = 0.012). Metachronous ESCC and HNSCC were more common in the double-inactivated group (P < 0.001, P = 0.001). Multivariate analysis identified located in the upper esophagus, multiple LVLs and history of HNSCC as risk factors for metachronous ESCC.

CONCLUSIONS

Activation patterns of alcohol-metabolizing enzymes were related to age at ESCC onset, lesion location, and metachronous ESCC and HNSCC. Different approaches to the prophylaxis and treatment of esophageal cancer should be considered, depending on the enzyme activity pattern.

Protective effects of Alda-1, an ALDH2 activator, on alcohol-derived DNA damage in the esophagus of human ALDH2*2 (Glu504Lys) knock-in mice

Alcohol consumption is the key risk factor for the development of esophageal squamous cell carcinoma (ESCC), and acetaldehyde, a metabolite of alcohol, is an alcohol-derived major carcinogen that causes DNA damage. Aldehyde dehydrogenase2 (ALDH2) is an enzyme that detoxifies acetaldehyde, and its activity is reduced by ALDH2 gene polymorphism. Reduction in ALDH2 activity increases blood, salivary and breath acetaldehyde levels after alcohol intake, and it is deeply associated with the development of ESCC. Heavy alcohol consumption in individuals with ALDH2 gene polymorphism significantly elevates the risk of ESCC; however, effective prevention has not been established yet. In this study, we investigated the protective effects of Alda-1, a small molecule ALDH2 activator, on alcohol-mediated esophageal DNA damage. Here, we generated novel genetically engineered knock-in mice that express the human ALDH2*1 (wild-type allele) or ALDH2*2 gene (mutant allele). Those mice were crossed, and human ALDH2*1/*1, ALDH2*1/*2 and ALDH2*2/*2 knock-in mice were established. They were given 10% ethanol for 7 days in the presence or absence of Alda-1, and we measured the levels of esophageal DNA damage, represented by DNA adduct (N²-ethylidene-2′-deoxyguanosine). Alda-1 significantly increased hepatic ALDH2 activity both in human ALDH2*1/*2 and/or ALDH2*2/*2 knock-in mice and reduced esophageal DNA damage levels after alcohol drinking. Conversely, cyanamide, an ALDH2-inhibitor, significantly exacerbated esophageal DNA adduct level in C57BL/6N mice induced by alcohol drinking. These results indicate the protective effects of ALDH2 activation by Alda-1 on esophageal DNA damage levels in individuals with ALDH2 gene polymorphism, providing a new insight into acetaldehyde-mediated esophageal carcinogenesis and prevention.

Association of ADH1B Arg47His polymorphism with the risk of cancer: a meta-analysis

Alcohol consumption has been established to be a major factor in the development and progress of cancer. Genetic polymorphisms of alcohol-metabolism genes result in differences between individuals in exposure to acetaldehyde, leading to possible carcinogenic effects. Arg47His (rs1229984 G > A) in ADH1B have been frequently studied for its potential effect on carcinogenesis. However, the findings are as yet inconclusive. To gain a more precise estimate of this potential association, we conducted a meta-analysis including 66 studies from 64 articles with 31999 cases and 50964 controls. The pooled results indicated that ADH1B Arg47His polymorphism is significantly associated with the decreased risk of overall cancer (homozygous model, odds ratio (OR) = 0.62, 95% confidence interval (CI) = 0.49–0.77; heterozygous model, OR = 0.71, 95% CI = 0.60–0.84; recessive model, OR = 0.83, 95% CI = 0.76–0.91; dominant model, OR = 0.62, 95% CI = 0.53–0.72; and allele comparison, OR = 0.82, 95% CI = 0.75–0.89). Stratified analysis by cancer type and ethnicity showed that a decreased risk was associated with esophageal cancer and head and neck cancer amongst Asians. In conclusion, our meta-analysis suggested that ADH1B Arg47His polymorphism was significantly associated with decreased overall cancer risk. These findings need further validation in large multicenter investigations.

Effect of ALDH2 polymorphism on cancer risk in Asians: A meta-analysis

Numerous studies have investigated the association between ALDH2 gene rs671G>A polymorphism and various cancer type in Asians. However, the results remain inconclusive.We conducted a comprehensive meta-analysis including 63 articles with 66 studies containing 25,682 cases and 47,455 controls retrieved by searching PubMed and Embase electronic databases up to March 5, 2018.Pooled results indicated that ALDH2 gene rs671 polymorphism was significantly associated with the overall cancer risk in Asians (homozygous model: odds ratio [OR] = 0.85, 95% confidence interval [CI] = 0.72-0.99, P = .042; heterozygous model: OR = 1.32, 95% CI = 1.14-1.52, P  < .001; recessive model: OR = 0.73, 95% CI = 0.60-0.88, P = .001; dominant model: OR = 1.32, 95% CI = 1.16-1.51, P < .001; and allele comparison model: OR = 1.11, 95% CI = 1.03-1.19, P = .004), especially in esophageal cancer and among the Chinese and the Japanese.Our results suggest that ALDH2 rs671 polymorphism is associated with the overall cancer risk in Asians. Well-designed prospective studies with more information about gene-environment interaction, such as drinking, should be conducted to validate our findings.

Clinical and translational advances in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is among the most deadly forms of human malignancy characterized by late stage diagnosis, metastasis, therapy resistance and frequent recurrence. Clinical management of ESCC remains challenging and the disease presently lacks approved targeted therapeutics. However, emerging data from recent clinical and translational investigations hold great promise for future progress toward improving patient outcomes in this deadly disease. Here, we review current clinical perspectives in ESCC epidemiology, pathophysiology, and clinical care, highlighting recent advances with potential to impact ESCC prevention, diagnosis and management. We further provide an overview of recent translational investigations contributing to our understanding of the molecular mechanisms underlying ESCC development, progression and therapy response, including insights gained from genetic studies and various murine model systems. Finally, we discuss future perspectives in the clinical and translational realms, along with remaining hurdles that must be overcome to eradicate ESCC.

Association of ALDH3B2 gene polymorphism and risk factors with susceptibility of esophageal squamous cell carcinoma in a Chinese population: a case-control study involving 2,358 subjects

Background

Esophageal cancer (EC) is the sixth leading cause of cancer-associated death worldwide. The interaction of environmental risk factors and genetic factors might contribute to the carcinogenesis of EC synergistically.

Results

All seven single locus polymorphisms of ALDH3B2 were not associated with risk of ESCC as evaluated by allelic, dominant, co-dominant, recessive and Cochran-Armitage trend tests. Stratified analyses showed these SNPs were not correlated with the susceptibility of ESCC according to different age, gender, cigarette smoking and alcohol drinking status. None of the major haplotypes were related with ESCC susceptibility.

Materials and Methods

We conducted a hospital-based case-control study to evaluate the combined effects of environmental risk factors and the single nucleotide polymorphisms (SNPs) of ALDH3B2 gene on the development of esophageal squamous carcinoma (ESCC). A total of 1043 ESCC cases and 1315 controls were recruited for this study. Seven ALDH3B2 SNPs and four environmental factors were selected as independent variables. ALDH3B2 SNPs were determined by ligation detection reaction method.

Conclusions

Our study suggested that ALDH3B2 rs34589365, rs3741172, rs4646823, rs78402723, rs7947978, rs866907 and rs9787887 polymorphisms were not implicated with altered susceptibility of ESCC according to different age, gender, cigarette smoking and alcohol drinking status. Yet this conclusion needs to be verified in larger studies among different ethnic populations with validation design, the biological function of these SNPs in carcinogenesis are subject to further investigation.

Cytochrome P450 1A1 gene polymorphisms and digestive tract cancer susceptibility: a meta-analysis

Cytochrome P450 1A1 (CYP1A1) is a phase I enzyme that regulates the metabolism of environmental carcinogens and alter the susceptibility to various cancers. Many studies have investigated the association between the CYP1A1 MspI and Ile462Val polymorphisms and digestive tract cancer (DTC) risk in different groups of populations, but their results were inconsistent. The PubMed and Embase Database were searched for case–control studies published up to 30th September, 2015. Data were extracted and pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess the relationship. Totally, 39 case–control studies (9094 cases and 12,487 controls) were included. The G allele in Ile/Val polymorphism was significantly associated with elevated DTC risk with per‐allele OR of 1.24 (95% CI = 1.09–1.41, P = 0.001). Similar results were also detected under the other genetic models. Evidence was only found to support an association between MspI polymorphism and DTC in the subgroups of caucasian and mixed individuals, but not in the whole population (the dominant model: OR = 1.19, 95% CI = 0.94–1.91, P = 0.146). In conclusion, our results suggest that the CYP1A1 polymorphisms are potential risk factors for DTC. And large sample size and well‐designed studies with detailed clinical information are needed to more precisely evaluate our founding.

Glutathione S-transferase M1 polymorphism and esophageal cancer risk: An updated meta-analysis based on 37 studies

AIM: To evaluate the relationship between glutathione S-transferase M1 (GSTM1) polymorphism and susceptibility to esophageal cancer (EC).

METHODS: A comprehensive search of the United States National Library of Medicine PubMed database and the Elsevier, Springer, and China National Knowledge Infrastructure databases for all relevant studies was conducted using combinations of the following terms: “glutathione S-transferase M1”, “GSTM1”, “polymorphism”, and “EC” (until November 1, 2014). The statistical analysis was performed using the SAS software (v.9.1.3; SAS Institute, Cary, NC, United States) and the Review Manager software (v.5.0; Oxford, England); crude odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the association between the GSTM1 null genotype and the risk of EC.

RESULTS: A total of 37 studies involving 2236 EC cases and 3243 controls were included in this meta-analysis. We observed that the GSTM1 null genotype was a significant risk factor for EC in most populations (OR = 1.33, 95%CI: 1.12-1.57, P_{heterogeneity} < 0.000001, and I² = 77.0%), particularly in the Asian population (OR = 1.53, 95%CI: 1.26-1.86, P_{heterogeneity} < 0.000001, and I² = 77.0%), but not in the Caucasian population (OR = 1.02, 95%CI: 0.87-1.19, P_{heterogeneity} = 0.97, and I² = 0%).

CONCLUSION: The GSTM1 null polymorphism may be associated with an increased risk for EC in Asian but not Caucasian populations.

Association of CYP1A1 MspI polymorphism in the esophageal cancer risk: a meta-analysis in the Chinese population

Background

Although many epidemiologic studies have investigated the CYP1A1 MspI gene polymorphisms and their associations with esophageal cancer (EC), definite conclusions cannot be drawn. To clarify the effects of CYP1A1 MspI polymorphisms on the risk of EC, a meta-analysis was performed in Chinese population.

Methods

Related studies were identified from PubMed, Springer Link, Ovid, Chinese Wanfang Data Knowledge Service Platform, Chinese National Knowledge Infrastructure (CNKI), and Chinese Biology Medicine (CBM) till October 2014. Pooled ORs and 95% CIs were used to assess the strength of the associations.

Results

A total of 13 studies including 1,519 EC cases and 1,962 controls were involved in this meta-analysis. Overall, significant association was found between CYP1A1 MspI polymorphism and EC risk when all studies in the Chinese population pooled into this meta-analysis (C vs. T: OR = 1.25, 95% CI = 1.04 to 1.51; CC + CT vs. TT: OR = 1.35, 95% CI = 1.06 to 1.72; CC vs. TT + CT: OR = 1.35, 95% CI = 1.03 to 1.76). When we performed stratified analyses by geographical locations, histopathology type, and source of control, significantly increased risks were found in North China (C vs. T: OR = 1.38, 95% CI = 1.12 to 1.70; CC vs. TT: OR = 1.72, 95% CI = 1.16 to 2.56; CC + CT vs. TT: OR = 1.52, 95% CI = 1.14 to 2.02; CC vs. TT + CT: OR = 1.55, 95% CI = 1.17 to 2.06), in the population-based studies (C vs. T: OR = 1.22, 95% CI = 1.05 to 1.42; CC vs. TT: OR = 1.38, 95% CI = 1.02 to 1.88; CC + CT vs. TT: OR = 1.36, 95% CI = 1.10 to 1.69; CC vs. TT + CT: OR = 1.43, 95% CI = 1.13 to 1.81) and ESCC (C vs. T: OR = 1.17, 95% CI = 1.04 to 1.32; CC + CT vs. TT: OR = 1.28, 95% CI = 1.08 to 1.52).

Conclusions

This meta-analysis provides the evidence that CYP1A1 MspI polymorphism may contribute to the EC development in the Chinese population.

Clinical significance of ALDH2 rs671 polymorphism in esophageal cancer: evidence from 31 case-control studies

Background

Aldehyde dehydrogenase 2 (ALDH2), a critical enzyme for the detoxification of alcohol, is associated with many types of cancers. To verify the relationship of ALDH2 rs671 G>A polymorphism and esophageal cancer (EC), we performed a meta-analysis of a total of 31 published data including 8,510 patients and 16,197 controls.

Methods

The pooled odds ratio (OR) and the 95% confidence interval (CI) were calculated using a fixed or random-effects model. Heterogeneity (P_H), publication bias, and sensitivity analysis were also determined.

Results

Although a protective effort was found in the rs671 homozygote comparison (AA/GG: OR=0.69; 95% CI=0.48–0.98), the heterozygote comparison was apparently associated with the risk of EC, particularly in the Chinese population (AG/GG: OR=1.39; 95% CI=1.03–1.87). Alcohol consumption remarkably increased this risk, especially in the AG genotype. Drinking men with the AG genotype appeared to show a higher risk (AG/GG: OR=4.39; 95% CI=1.24–6.55) than drinking women.

Conclusion

The present meta-analysis provided advanced information regarding the association of the ALDH2 A>G polymorphism and EC. Taken together, insights from this study suggested an enhanced effect on the development of EC through a genetic–environmental interaction.

Improved body weight and performance status and reduced serum PGE2 levels after nutritional intervention with a specific medical food in newly diagnosed patients with esophageal cancer or adenocarcinoma of the gastro-esophageal junction

BACKGROUND

The majority of cancer patients loses weight and becomes malnourished during the course of their disease. Metabolic alterations and reduced immune competence lead to wasting and an increased risk of infectious complications. In the present study, the effect of a nutritionally complete medical food, which is high in protein and leucine and enriched with fish oil and specific oligosaccharides, was investigated on immune function, nutritional status, and inflammation in patients with esophageal cancer and compared with routine care.

METHODS

In this exploratory double-blind study, 64 newly diagnosed esophageal cancer patients were randomized. All patients received dietary counselling and dietary advice. In the Active group, all patients received the specific medical food for 4 weeks before the start of anticancer therapy. In the routine care control arm, patients with <5% weight loss received a non-caloric placebo product, and patients with weight loss ≥5% received an iso-caloric control product to secure blinding of the study. The required study parameters of body weight and performance status were recorded at baseline and after 4 weeks of nutritional intervention, and patients were asked to complete quality of life questionnaires. In addition, blood samples were taken for the measurement of several immune, nutritional, and safety-parameters.

RESULTS

No effect of the specific nutritional intervention could be detected on ex vivo stimulations of blood mononuclear cells. By contrast, body weight was significantly increased (P < 0.05) and ECOG performance status was improved after intervention with the specific medical food (P < 0.05). In addition, serum Prostaglandin E2 (PGE2) levels were significantly decreased in the specific medical food group and increased in the control group (P = 0.002).

CONCLUSIONS

Nutritional intervention with the specific medical food significantly increased body weight and improved performance status compared with routine care in newly diagnosed esophageal cancer patients. This effect was accompanied by significantly reduced serum PGE2 levels.

Association between Glu504Lys polymorphism of ALDH2 gene and cancer risk: a meta-analysis

Background

The association of the aldehyde dehydrogenases-2 (ALDH2) Glu504Lys polymorphism (also named Glu487Lys, or rs671) and cancers has been investigated. This meta-analysis aims to comprehensively assess the influence of this polymorphism on the overall cancer risk.

Methods

Eligible publications were retrieved according to inclusion/exclusion criteria and the data were analyzed using the Review Manager software (V5.2).

Results

A meta-analysis based on 51 case-control studies consisting of 16774 cases and 32060 controls was performed to evaluate the association between the ALDH2 Glu504Lys polymorphism and cancer risk. The comparison of genotypes Lys+ (Lys/Lys and Lys/Glu) with Glu/Glu yielded a significant 20% increased cancer risk (OR = 1.20, 95%CI: 1.03–1.39, P = 0.02, I² = 92%). Subgroup analysis by cancer type indicated a significantly increased UADT cancer risk (OR = 1.39, 95%CI: 1.11–1.73, P = 0.004, I² = 94%) in individuals with the Lys+ genotypes. Subgroup analysis by country indicated that individuals from Japan with the Lys+ genotypes had a significant 38% increased cancer risk (OR = 1.38, 95%CI: 1.12–1.71, P = 0.003, I² = 93%).

Conclusions

Our results indicated that the ALDH2 Glu504Lys polymorphism is a susceptible loci associated with overall cancers, especially esophageal cancer and among Japanese population.

Cytochrome P450 1A1 (CYP1A1) polymorphism and susceptibility to esophageal cancer: an updated meta-analysis of 27 studies

Cytochrome P450 1A1 (CYP1A1) polymorphisms are known to play a crucial role in the development and metastasis of malignant diseases including esophageal cancer. However, the results of previous studies investigating the association between CYP1A1 polymorphisms and esophageal cancer risk have been inconsistent. This meta-analysis of 27 eligible studies, encompassing 4,215 esophageal cancer cases and 6,339 control subjects, pooled the odds ratios (ORs) with corresponding 95 % confidence intervals (95 % CI) to assess this association. The effects of ethnicity (Caucasian and Asian) and histopathology type (esophageal squamous cell carcinoma and esophageal adenocarcinoma) were considered in subgroup analyses. A significant association was observed between the CYP1A1 Ile/Val gene polymorphism and esophageal cancer in all of the genetic models (Ile/Val vs. Ile/Ile, OR = 1.41, 95 % CI = 1.25-1.58; Val/Val vs. Ile/Ile, OR = 1.94, 95 % CI = 1.34-2.82; Ile/Val + Val/Val vs. Ile/Ile, OR = 1.49, 95 % CI = 1.33-1.66). The subgroup analysis based on ethnicity showed that the association between the CYP1A1 Ile/Val polymorphism and esophageal cancer existed in Asian and Caucasian populations. However, no association was observed between the CYP1A1 MspI polymorphism and esophageal cancer in either subgroup or in the overall population. These results suggested that the CYP1A1 Ile/Val polymorphism was associated with an increased risk of esophageal cancer, whereas the CYP1A1 MspI polymorphism may not have increased susceptibility to esophageal cancer. Further studies are required to confirm these findings.

Tag single nucleotide polymorphisms of alcohol-metabolizing enzymes modify the risk of upper aerodigestive tract cancers: HapMap database analysis

Although alcohol is associated with higher upper aerodigestive tract (UADT) cancer risk, only a small fraction of alcoholics develop cancers. There is a lack of evidence proving the association of tag single nucleotide polymorphisms of alcohol-metabolizing enzymes with cancer risk. The aim of this study was to determine the association of these genetic polymorphisms with UADT cancer risk in a Chinese population. It was a hospital-based case-control candidate gene study. The databases of the International HapMap Project were searched for haplotype tag single nucleotide polymorphisms of the genes alcohol dehydrogenase (ADH)1B, ADH1C, and aldehyde dehydrogenase (ALDH)2. The genotyping was performed by the Sequenom MassARRAY system. Totally, 120 head and neck squamous cell carcinoma, 138 esophageal squamous cell carcinoma patients, and 276 age- and gender-matched subjects were enrolled between June 2008 and June 2010.Minor alleles of ADH1B (rs1229984) and ALDH2(rs671) were not only associated with the risk of UADT cancers (odds ratio [OR] [95% confidence interval, CI]: 3.53 [2.14-5.80] and 2.59 [1.79-3.75], respectively) but also potentiated the carcinogenic effects of alcohol (OR [95% CI]: 53.44 [25.21-113.29] and 70.08 [33.65-145.95], respectively). Similar effects were observed for head/neck and esophageal cancer subgroups. Multivariate logistic regression analysis identified four significant risk factors, including habitual use of cigarettes, alcohol, betel quid, and lower body mass index (P < 0.001). The haplotypes GAGC (OR 1.61, 95% CI 1.08-2.40, P = 0.018) and CCAATG (OR 1.69, 95% CI 1.24-2.30, P < 0.001) on chromosomes 4 and 12, respectively, were associated with higher cancer risk. These findings suggested that risk allele or haplotype carriers who consume alcohol and other carcinogens should be advised to undergo endoscopy screening. The information can be used to determine the degree of susceptibility of each subject and can be combined with other environmental factors, like carcinogen consumption, in the screening analysis.

CYP1A1 genetic polymorphisms and risk for esophageal cancer: a case-control study in central China

The purpose of this study was to evaluate the associations of CYP1A1 genetic polymorphisms with the risk of developing esophageal cancer (EC). A case-control study was carried out in a Chinese population in which 157 hospital based EC cases and 157 population based healthy controls with 1:1 match by age and sex were included. PCR based restriction fragment length polymorphisms (PCR-RFLP) were used to detect genotypes in case and control groups. For the CYP1A1 Ile/Val polymorphism, comparing with wild genotype Ile/Ile, both the heterozygote genotype Ile/Val and the combined variant genotype Ile/Val+Val/Val increased the risk of esophageal cancer (OR: 2.05, 95%CI: 1.19-3.54, OR: 1.86, 95%CI: 1.11-3.12). No significant association was found between the CYP1A1 MspI polymorphism and EC. According to analysis of combined genotypes, the TC/AG combined genotype which contained both variant alleles of these two polymorphisms increased the risk of developing EC (OR: 2.12, 95%CI: 1.16-3.85). Our results suggested that genetic polymorphisms of CYP1A1 may increase the susceptibility to EC.

Association between CYP1A1 polymorphisms and esophageal cancer: a meta-analysis

Cytochrome P4501A1 (CYP1A1) enzyme is a member of the CYP superfamily of enzymes. CYP1A1 A2455G and T3801C are two most commonly studied polymorphisms loci. Previous studies have reported that CYP1A1 polymorphisms increase esophageal cancer (EC) risk. However, the results remain controversial and ambiguous. To further investigate the association between CYP1A1 polymorphisms (A2455G and T3801C) and EC risk. A meta-analysis was performed to investigate the association between CYP1A1 polymorphisms and EC risk. A total of 13 articles (A2455G and T3801C: 2 papers, A2455G: 8 papers, T3801C: 3 papers) from the PubMed containing information on the CYP1A1 polymorphisms and EC were included in this meta-analysis, with summational sample size of 1,881 EC cases and 3,786 controls. Stratified analysis was performed to evaluate the ethnicity (Caucasians and Asian) and histopathology type (esophageal squamous cell carcinoma and esophageal adenocarcinoma) effect. No obvious publication bias in the two polymorphisms was observed. Our meta-analysis revealed a significant association between the A2455G polymorphism and EC (OR = 1.55 per A allele, 95 % CI 1.29-1.85, P < 0.001). Stratification analysis by ethnicity and histopathology type showed significant association in the population of Asian origin (OR = 1.55, 95 % CI 1.28-1.89, P < 0.001) and in histopathology type of ESCC (OR = 1.40, 95 % CI 1.19-1.65, P < 0.001). We didn't observe the significant association between CYP1A1 T3801C polymorphism and EC. We observed a difference of allele frequencies between Caucasian and Asian population in the meta-analysis. The allele frequencies in our meta-analysis were consistent with the allele frequencies in 1000 Genome Project. Our meta-analysis demonstrated distinct evidence that CYP1A1 A2455G polymorphism was associated with the risk of EC.

GSTM1 and GSTT1 polymorphism and susceptibility to esophageal cancer in high- and low-risk regions of India

Glutathione transferases, a super family of dimeric phase II metabolic enzymes play a vital role in biotransformation of many substances. This study evaluates the influence of genetic polymorphism of GSTM1 and GSTT1 gene loci on esophageal cancer risk in Assam and Delhi from India. DNA from blood samples of esophageal cancer cases (203,112) and controls (286,150) from Assam and Delhi, respectively, were extracted. GSTM1 and GSTT1 polymorphisms were analyzed by multiplex PCR procedure. Differences in proportions were tested using Pearson's chi-square test with odds ratio (OR) and 95 % confidence interval (CI). Risk of esophageal cancer was approximately twice in individuals having homozygous GSTM1 (OR-2.1, 95 % CI, 1.44-3.13) and GSTT1 null genotypes (OR-1.7,95 % CI, 0.99-2.77) in Assam, and around three times in GSTT1 null genotype (OR-2.9, 95 % CI, 1.56-5.27) in Delhi population. GSTM1 null genotype seems to play a protective role (OR-0.7, 95 % CI, 0.39-1.27) in Delhi. A significant association of GSTM1 null genotype with esophageal cancer was observed in a younger age group in Assam (OR-2.7, 95 % CI, 1.48-5.01), and in Delhi population association was observed in smokers with GSTT1 null genotype (OR-2.5, 95 % CI, 1.04-6.07), and alcoholics having GSTM1 null genotype (OR-2.6, 95 % CI, 0.99-6.77). Significant association of GSTM1 null genotype in Assam was observed between cancer cases and controls in fermented betel nut chewers only (OR-2.8, 95 % CI, 1.19-6.72), whereas, smoking and alcohol failed to show any correlation with GSTM1/GSTT1 genotypes. Cancer development is not only due to exogenous or endogenous carcinogens but depends on their interaction with genes that are involved in the detoxification of these carcinogens.

Cytochrome P450 2E1 RsaI/PstI polymorphism and risk of esophageal cancer: A meta-analysis of 17 case-control studies

The aim of this study was to explore the cytochrome P450 2E1 (CYP2E1) RsaI/PstI polymorphism and risk of esophageal cancer (EC) in mainland Chinese populations. A systematic search of PubMed, EMBASE, Web of Science, CBM, CNKI and VIP databases for publications on the CYP2E1 RsaI/PstI polymorphism and risk of EC was performed. and the genotype data were analyzed in a meta-analysis. Odds ratios (ORs) with relevant 95% confidence intervals (CIs) were estimated to assess the association. Sensitivity analysis, test of heterogeneity and assessment of publication bias were performed. The search yielded 17 studies including 18 trails involving 1,663 cases and 2,603 controls. The meta-analyses showed a significant association between the CYP2E1 RsaI/PstI polymorphism and risk of EC in the mainland Chinese population (c2 vs. c1: OR=0.64; 95% CI, 0.50-0.81; P<0.001; c2/c2 vs. c1/c1: OR=0.73; 95% CI, 0.57-0.93; c2/c2 vs. c1/c1+c1/c2: OR=0.76; 95% CI, 0.60-0.96; P=0.02; c1/c2 vs. c1/c1: OR=0.54; 95% CI, 0.38-0.75; P<0.001; c1/c2+c2/c2 vs. c1/c1: OR=0.48; 95% CI, 0.34-0.70; P<0.001). An increased cancer risk in all genetic models was identified following stratification by ethnicity, source of controls and tumor type. In conclusion, in all genetic models, the association between the CYP2E1 RsaI/PstI polymorphism and risk of EC in the mainland Chinese population was significant. This meta-analysis suggests that the CYP2E1 RsaI/PstI polymorphism is a risk factor for EC, and the c2 allele is a factor that lowers the possibility of EC in the mainland Chinese population and this association did not change due to ethnic differences in genetic backgrounds and the environment.

Alcohol dehydrogenase-1B Arg47His polymorphism and upper aerodigestive tract cancer risk: a meta-analysis including 24,252 subjects

BACKGROUND

Cancers of the upper aerodigestive tract (UADT) include malignant tumors of the oral cavity, pharynx, larynx, and esophagus, account for approximately 4% of all new cancers in world. Alcohol drinking is an established risk factor for UADT cancers, and the rate of alcohol metabolism could significantly been influenced by genetic polymorphisms of alcohol dehydrogenase-1B (ADH1B) His47Arg (rs1229984). To evaluate whether combined evidence shows ADH1B His47Arg as a common genetic variant that influenced the risk of UADT cancers, we considered all available studies in a meta-analysis.

METHODS

Eighteen studies were combined representing data of 8,539 cases and 15,713 controls for meta-analysis. Stratified analyses were carried out to determine the gene-environment interaction between ADH1B His47Arg and alcohol drinking and gene-gene interaction between ADH1B His47Arg and aldehyde dehydrogenase-2 (ALDH2) Glu/Lys related to UADT cancer risk. Potential sources of heterogeneity between studies were explored; sensitivity analysis and publication bias was also evaluated.

RESULTS

The ADH1B 47Arg allele was found to be associated with increased risk of UADT cancers, the pooled odds ratios (ORs) being 1.66 (95% CI: 1.54 to 1.79) and 3.47 (95% CI: 2.76 to 4.36) for the His/Arg and Arg/Arg genotypes compared with the His/His genotype, respectively. An 18.48-fold increase in OR (95% CI: 12.95 to 26.40) for UADT cancers among alcohol drinkers with Arg/Arg genotype was found, when compared among nondrinkers with the His/His genotype. Significant interaction between carriers with ADH1B 47Arg and ALDH2 487Lys allele related to risk for UADT cancers was more evident, compared with noncarriers (OR = 10.31, 95% CI: 5.45 to 18.85).

CONCLUSIONS

ADH1B 47Arg allele is a common genetic variant that increased the risk of UADT cancers; furthermore, it modulates the susceptibility to UADT cancers coupled with alcohol drinking and interaction with the ALDH2 487Lys allele.

Sequence Variants and the Risk of Head and Neck Cancer: Pooled Analysis in the INHANCE Consortium

Previous molecular epidemiological studies on head and neck cancer have examined various single nucleotide polymorphisms (SNPs), but there are very few documented associations. In the International head and neck cancer epidemiology (INHANCE) consortium, we evaluated associations between SNPs in the metabolism, cell cycle, and DNA repair pathways and the risk of head and neck cancer. We analyzed individual-level pooled data from 14 European, North American, Central American, and Asia case-control studies (5,915 head and neck cancer cases and 10,644 controls) participating in the INHANCE consortium. Unconditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) for SNP effects, adjusting for age, sex, race, and country. We observed an association between head and neck cancer risk and MGMT Leu84Phe heterozygotes (OR = 0.79, 95% CI = 0.68-0.93), XRCC1 Arg194Trp homozygotes Arg/Arg (OR = 2.3, 95% CI = 1.1-4.7), ADH1B Arg48His homozygotes Arg/Arg (OR = 2.7, 95% CI = 1.9-4.0), ADH1C Ile350Val homozygotes Ile/Ile (OR = 1.2, 95% CI = 1.1-1.4), and the GSTM1 null genotype (OR = 1.1, 95% CI = 1.0-1.2). Among these results, MGMT Leu84Phe, ADH1B Arg48His, ADH1C Ile350Arg, and the GSTM1 null genotype had fairly low false positive report probabilities (<20%). We observed associations between ADH1B Arg48His, ADH1C Ile350Arg, and GSTM1 null genotype and head and neck cancer risk. No functional study currently supports the observed association for MGMT Leu84Phe, and the association with XRCC1 Arg194Trp may be a chance finding.

Multi-susceptibility genes associated with the risk of the development stages of esophageal squamous cell cancer in Feicheng County

BACKGROUND

The purpose of this study was to evaluate the association of multi-genotype polymorphisms with the stepwise progression of esophageal squamous cell cancer (ESCC) and the possibility of predicting those at higher risk.

METHODS

A total of 1,004 subjects were recruited from Feicheng County, China, between Jan. 2004 and Dec. 2007 and examined by endoscopy for esophageal lesions. These subjects included 270 patients with basal cell hyperplasia (BCH), 262 patients with esophageal squamous cell dysplasia (ESCD), 226 patients with ESCC, and 246 controls with Lugol-voiding area but diagnosed as having normal esophageal squamous epithelial cells by histopathology. The genotypes for CYP2E1 G1259C, hOGG1 C326G, MTHFR C677T, MPO G463A, and ALDH2 allele genes were identified in blood samples collected from all participants.

RESULTS

The alleles ALDH2 and MTHFR C677T were critical for determining individual susceptibility to esophageal cancer. Compared to the ALDH 1*1 genotype, the ALDH 2*2 genotype was significantly associated with increased risks of BCH, ESCD, and ESCC. However, the TT genotype of MTHFR C677T only increased the risk of ESCC. Further analysis revealed that the combination of the high-risk genotypes 2*2/1*2 of ALDH 2 and TT/TC of MTHFR C677T increased the risk of BCH by 4.0 fold, of ESCD by 3.7 fold, and ESSC by 8.72 fold. The generalized odds ratio (ORG) of the two combined genotypes was 1.83 (95%CI: 1.55-2.16), indicating a strong genetic association with the risk of carcinogenic progression in the esophagus.

CONCLUSIONS

The study demonstrated that the genotypes ALDH2*2 and MTHFR 677TT conferred elevated risk for developing esophageal carcinoma and that the two susceptibility genotypes combined to synergistically increase the risk.

Multi-susceptibility genes associated with the risk of the development stages of esophageal squamous cell cancer in Feicheng County

Background

The purpose of this study was to evaluate the association of multi-genotype polymorphisms with the stepwise progression of esophageal squamous cell cancer (ESCC) and the possibility of predicting those at higher risk.

Methods

A total of 1,004 subjects were recruited from Feicheng County, China, between Jan. 2004 and Dec. 2007 and examined by endoscopy for esophageal lesions. These subjects included 270 patients with basal cell hyperplasia (BCH), 262 patients with esophageal squamous cell dysplasia (ESCD), 226 patients with ESCC, and 246 controls with Lugol-voiding area but diagnosed as having normal esophageal squamous epithelial cells by histopathology. The genotypes for CYP2E1 G1259C, hOGG1 C326G, MTHFR C677T, MPO G463A, and ALDH2 allele genes were identified in blood samples collected from all participants.

Results

The alleles ALDH2 and MTHFR C677T were critical for determining individual susceptibility to esophageal cancer. Compared to the ALDH 1*1 genotype, the ALDH 2*2 genotype was significantly associated with increased risks of BCH, ESCD, and ESCC. However, the TT genotype of MTHFR C677T only increased the risk of ESCC. Further analysis revealed that the combination of the high-risk genotypes 2*2/1*2 of ALDH 2 and TT/TC of MTHFR C677T increased the risk of BCH by 4.0 fold, of ESCD by 3.7 fold, and ESSC by 8.72 fold. The generalized odds ratio (OR_G) of the two combined genotypes was 1.83 (95%CI: 1.55-2.16), indicating a strong genetic association with the risk of carcinogenic progression in the esophagus.

Conclusions

The study demonstrated that the genotypes ALDH2*2 and MTHFR 677TT conferred elevated risk for developing esophageal carcinoma and that the two susceptibility genotypes combined to synergistically increase the risk.

Alcohol and aldehyde dehydrogenase polymorphisms and a new strategy for prevention and screening for cancer in the upper aerodigestive tract in East Asians

The ethanol in alcoholic beverages and the acetaldehyde associated with alcohol consumption are Group 1 human carcinogens (WHO, International Agency for Research on Cancer). The combination of alcohol consumption, tobacco smoking, the inactive heterozygous aldehyde dehydrogenase-2 genotype (ALDH2*1/*2) and the less-active homozygous alcohol dehydrogenase-1B genotype (ADH1B*1/*1) increases the risk of squamous cell carcinoma (SCC) in the upper aerodigestive tract (UADT) in a multiplicative fashion in East Asians. In addition to being exposed to locally high levels of ethanol, the UADT is exposed to a very high concentration of acetaldehyde from a variety of sources, including that as an ingredient of alcoholic beverages per se and that found in tobacco smoke; acetaldehyde is also produced by salivary microorganisms and mucosal enzymes and is present as blood acetaldehyde. The inefficient degradation of acetaldehyde by weakly expressed ALDH2 in the UADT may be cri! tical to the local accumulation of acetaldehyde, especially in ALDH2*1/*2 carriers. ADH1B*1/*1 carriers tend to experience less intense alcohol flushing and are highly susceptible to heavy drinking and alcoholism. Heavy drinking by persons with the less-active ADH1B*1/*1 leads to longer exposure of the UADT to salivary ethanol and acetaldehyde. The ALDH2*1/*2 genotype is a very strong predictor of synchronous and metachronous multiple SCCs in the UADT. High red cell mean corpuscular volume (MCV), esophageal dysplasia, and melanosis in the UADT, all of which are frequently found in ALDH2*1/*2 drinkers, are useful for identifying high-risk individuals. We invented a simple flushing questionnaire that enables prediction of the ALDH2 phenotype. New health appraisal models that include ALDH2 genotype, the simple flushing questionnaire, or MCV are powerful tools for devising a new strategy for prevention and screening for UADT cancer in East Asians.

ADH1B Arg47His polymorphism is associated with esophageal cancer risk in high-incidence Asian population: evidence from a meta-analysis

BACKGROUND AND OBJECTIVES

Incidence of Esophageal squamous cell carcinoma (ESCC) is prevalent in Asian populations, especially in the ones from the "Asian esophageal cancer belt" along the Silk Road and the ones from East Asia (including Japan). Silk Road and Eastern Asia population genetics are relevant to the ancient population migration from central China. The Arg47His (rs1229984) polymorphism of ADH1B is the highest in East Asians, and ancient migrations along the Silk Road were thought to be contributive to a frequent ADH1B*47His allele in Central Asians. This polymorphism was identified as responsible for susceptibility in the first large-scale genome-wide association study of ESCC and that's explained by its modulation of alcohol oxidization capability. To investigate the association of ADH1B Arg47His with ESCC in Asian populations under a common ancestry scenario of the susceptibility loci, we combined all available studies into a meta-analysis.

METHODS

A dataset composed of 4,220 cases and 8,946 controls from twelve studies of Asian populations was analyzed for ADH1B Arg47His association with ESCC and its interactions with alcohol drinking and ALDH2 Glu504Lys. Heterogeneity among studies and their publication bias were also tested.

RESULTS

The ADH1B*47Arg allele was found to be associated to increased risk of ESCC, with the odds ratios (OR) being 1.62 (95% CI: 1.49-1.76) and 3.86 (2.96-5.03) for the His/Arg and the Arg/Arg genotypes, respectively. When compared with the His/His genotype of non-drinkers, the Arg/Arg genotype can interact with alcohol drinking and greatly increase the risk of ESCC (OR = 20.69, 95%CI: 5.09-84.13). Statistical tests also showed gene-gene interaction of ADH1B Arg+ with ALDH2 Lys+ can bring more risk to ESCC (OR  = 13.46, 95% CI: 2.32-78.07).

CONCLUSION

Revealed by this meta-analysis, ADH1B*47Arg as a common ancestral allele can significantly increase the risk of ESCC in Asians, especially when coupled with alcohol drinking or the ALDH2*504Lys allele.

Relationship between genetic polymorphisms of ALDH2 and ADH1B and esophageal cancer risk: A meta-analysis

AIM: To evaluate the contribution of alcohol dehydrogenase-1B (ADH1B) and aldehyde dehydrogenase-2 (ALDH2) polymorphisms to the risk of esophageal cancer.

METHODS: Nineteen articles were included by searching MEDLINE, EMBASE and the Chinese Biomedical Database, 13 on ADH1B and 18 on ALDH2. We performed a meta-analysis of case-control studies including 13 studies on ADH1B (cases/controls: 2390/7100) and 18 studies on ALDH2 (2631/6030).

RESULTS: The crude odds ratio [OR (95% confidence interval)] was 2.91 (2.04-4.14) for ADH1B*1/*1 (vs ADH1B*2/*2) and 1.32 (1.17-1.49) for ADH1B*1/*2. The crude OR for ALDH2*1/*2 (vs ALDH2*1/*1) was 2.52 (1.76-3.61). ADH1B*1/*1 increased the risk of esophageal cancer among never/rare [1.56 (0.93-2.61)], moderate [2.71 (1.37-5.35)], and heavy drinkers [3.22 (2.27-4.57)]. ADH1B*1/*2 was associated with a modest risk among moderate drinkers [1.43 (1.09-1.87)]. ALDH2*1/*2 increased the risk among never/rare [1.28 (0.91-1.80)], moderate [3.12 (1.95-5.01)], and heavy [7.12 (4.67-10.86)] drinkers, and among ex-drinkers [5.64 (1.57-20.25)]. ALDH2*2/*2 increased the risk among drinkers [4.42 (1.72-11.36)]. ADH1B*1/*1 plus ALDH2*1/*2 was associated with the highest risk for heavy drinkers [12.45 (2.9-53.46)]. The results of the meta-regression analysis showed that the effects of ADH1B*1/*1 and ALDH2*1/*2 increased with the level of alcohol consumption. ALDH2*1/*2 was associated with a high risk among Taiwan Chinese and Japanese drinkers, as opposed to a moderate risk among drinkers in high-incidence regions of Mainland China. ADH1B*1/*1 in heavy drinkers and ALDH2*1/*2 in moderate-to-heavy drinkers was associated with similarly high risk among both men and women.

CONCLUSION: ADH1B/ALDH2 genotypes affect the risk of esophageal cancer, and the risk is modified by alcohol consumption, ethnicity, and gender.

CYP2E1 Rsa I/Pst I polymorphism and esophageal cancer risk: a meta-analysis based on 1,088 cases and 2,238 controls

The common functional CYP2E1 Rsa I/Pst I polymorphism may influence the risk of esophageal cancer. However, the published results are conflicting. We therefore conducted a meta-analysis comprised of 11 published case-control studies with 1,088 cases and 2,238 controls. Odds ratios (ORs) with 95% confidence interval (CIs) were used to assess the strength of the association. Overall, the pooled ORs were 0.53 (95% CI = 0.31-0.89, P (heterogeneity) < 0.001) and 0.57 (95% CI = 0.34-0.96, P (heterogeneity) < 0.001), for the heterogeneity c1/c2 and c2 allele carriers (c1/c2 + c2/c2) compared with the homozygous c1/c2, respectively. In subgroup analysis by race, the same significant risks were found among Asians (for c2 vs. c1: OR = 0.64, 95% CI = 0.43-0.95, P (heterogeneity) < 0.001; for c1/c2 vs. c1/c1: OR = 0.48, 95% CI = 0.28-0.82, P (heterogeneity) < 0.001; for c1/c2 + c2/c2 vs. c1/c1: OR = 0.51, 95% CI = 0.30-0.86, P (heterogeneity) < 0.001). In conclusion, our meta-analysis demonstrates that CYP2E1 Rsa I/Pst I c2 allele may be a decreased risk factor for developing esophageal cancer among Asians populations.

Effect of alcohol consumption, cigarette smoking and flushing response on esophageal cancer risk: a population-based cohort study (JPHC study)

We examined the effect of alcohol consumption, cigarette smoking and flushing response on esophageal squamous cell carcinoma (ESCC) in a large-scale population-based cohort study. 44,970 middle-aged and older Japanese men were followed. A total of 215 cases of ESCC were newly diagnosed. Alcohol consumption and cigarette smoking are strongly associated with the incidence of ESCC. Heavy alcohol consumption increased the risk of ESCC especially among heavy smokers with the flushing response (HR = 3.41, 95% CI = 2.10-5.51). Strong effect modification was detected in heavy smokers. Our results suggest that heavy alcohol consumption together with heavy smoking may increase the risk of ESCC particularly in individuals with the flushing response.

Genetic variations in esophageal cancer risk and prognosis

Investigations into inherited genetic variations in the DNA code (known as polymorphisms) in the field of oncology have provided preliminary support for an association with cancer risks and outcomes. Early studies have highlighted several genes with this potential predictive and prognostic power. However, these studies have had methodological limitations and have produced inconsistent results, making impractical as yet the routine evaluation of such genetic polymorphisms in general clinical practice. Continued research in this area is essential if we are to be able to soon use genetic polymorphisms to better select patients for targeted anticancer interventions. This review discusses the role of genetic polymorphisms and their association with esophageal cancer risk and prognosis. The article also highlights future directions in this new, emerging field of molecular epidemiology.

Association studies of CYP1A1 and GSTM1 polymorphisms with esophageal cancer risk: evidence-based meta-analyses

BACKGROUND AND AIMS

Previous studies have implicated cytochrome P450 1A1 (CYP1A1) and glutathione S-transferase M1 (GSTM1) polymorphisms as risk factors for various cancers. A number of studies have been devoted to the association of CYP1A1 or GSTM1 polymorphism with susceptibility to esophageal carcinoma and have yielded conflicting results. We undertook this study to assess possible associations of esophageal cancer risk with CYP1A1 genetic variation and GSTM1 null genotype, respectively.

METHODS

We conducted a search in MEDLINE, EMBASE and Chinese National Knowledge Infrastructure (CNKI) without a language limitation, covering all papers published until May 2008. The associated literature was acquired through deliberate searching and selected based on the established inclusion criteria for publications.

RESULTS

Ultimately, 26 studies met the included criteria and thus were selected. Relevant data were extracted and further analyzed using systematic meta-analyses. Results showed that the overall OR for CYP1A1 Msp1 polymorphism was 1.24 (95% CI = 0.84-1.83). Restricting analyses to ethnic groups and histological groups, data failed to show a correlation between CYP1A1 Msp1 polymorphism and esophageal cancer risk. Overall OR for CYP1A1 exon7 polymorphism was 1.37 (95% CI = 1.06-1.77), and subgroup analyses showed that CYP1A1 exon7 polymorphism increases esophageal cancer risk in Asians but not in Caucasians. As for GSTM1 deficiency, the overall OR was 1.20 (95% CI = 0.96-1.49), and further subgroup analyses failed to show a marked association of GSTM1 deletion with esophageal cancer.

CONCLUSIONS

Results of the present study suggest that CYP1A1 exon7 polymorphisms may be a risk factor for esophageal cancer in Asians but not in Caucasians, whereas neither CYP1A1 Msp1 nor GSTM1 polymorphism was associated with increased susceptibility to esophageal cancer.

Role of xenobiotic metabolic enzymes in cancer epidemiology

The cause of the majority of cancers is poorly understood albeit multifactorial. The ultimate consequence of etiological factors where defined is an alteration within the cellular genotype, which is manifested in the cells acquiring malignant phenotype. There are several environmental carcinogens that contribute to carcinogenesis. These carcinogens are metabolized by a large number of enzymes, including the cyto-chrome P 450 group, glutathione-S-transferase (GST), the uridine glucuronyl transferase (UGT) super-family, alcohol-metabolizing enzymes, sulphatases, etc. These enzymes can either inactivate carcinogens or in some cases generate reactive moieties that lead to carcinogenesis. This review summarises the available evidence regarding the role of xenobiotic metabolic enzymes and their role in cancer epidemiology. The available data and studies have identified correlates between expression of various metabolizing enzymes with risk of malignancies known to be induced by their substrates. The data may have relevance in one population but not for another for a specific malignancy and at times may be conflicting. We believe that with mature data in the future it may be possible to stratify patients by risk.

Polymorphisms of alcohol dehydrogenase 2 and aldehyde dehydrogenase 2 and colorectal cancer risk in Chinese males

AIM: To evaluate the relationship between drinking and polymorphisms of alcohol dehydrogenase 2 (ADH2) and/or aldehyde dehydrogenase 2 (ALDH2) for risk of colorectal cancer (CRC) in Chinese males.

METHODS: A case-control study was conducted in 190 cases and 223 population-based controls. ADH2 Arg47His (G-A) and ALDH2 Glu487Lys (G-A) genotypes were identified by PCR and denaturing high-performance liquid chromatography (DHPLC). Information on smoking and drinking was collected and odds ratio (OR) was estimated.

RESULTS: The ADH2 A/A and ALDH2 G/G genotypes showed moderately increased CRC risk. The age- and smoking-adjusted OR for ADH2 A/A relative to G/A and G/G was 1.60 (95% CI=1.08-2.36), and the adjusted OR for ALDH2 G/G relative to G/A and A/A was 1.79 (95% CI=1.19-2.69). Significant interactions between ADH2, ALDH2 and drinking were observed. As compared to the subjects with ADH2 G and ALDH2 A alleles, those with ADH2 A/A and ALDH2 G/G genotypes had a significantly increased OR (3.05, 95% CI= 1.67-5.57). The OR for CRC among drinkers with the ADH2 A/A genotype was increased to 3.44 (95% CI= 1.84-6.42) compared with non-drinkers with the ADH2 G allele. The OR for CRC among drinkers with the ALDH2 G/G genotype was also increased to 2.70 (95% CI= 1.57-4.66) compared with non-drinkers with the ALDH2 A allele.

CONCLUSION: Polymorphisms of the ADH2 and ALDH2 genes are significantly associated with CRC risk. There are also significant gene-gene and gene-environment interactions between drinking and ADH2 and ALDH2 polymorphisms regarding CRC risk in Chinese males.

Genetic polymorphisms of alcohol metabolising enzymes: their role in susceptibility to oesophageal cancer

BACKGROUND

Alcohol is a major risk factor for susceptibility to oesophageal cancer in the South African population. The role of polymorphisms in alcohol metabolising enzymes, alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH2) in predisposition of this population to oesophageal cancer is unknown. Alcohol metabolising enzymes exhibit polymorphisms that result in variant alleles with either increased or decreased activity.

METHODS

The role of these polymorphisms in increased risk of oesophageal cancer was investigated in 238 patients and 268 controls from Black and Mixed Ancestry South Africans, using the PCR/RFLP technique.

RESULTS

The ADH3*2/*2 genotype was significantly associated with increased risk for oesophageal cancer amongst Black subjects (odds ratio, 2.19; p=0.004). The low activity ALDH2*2 allele was significantly associated with increased risk for oesophageal cancer amongst the Black subjects (odds ratio, 2.35; p=0.0084).

CONCLUSIONS

It was observed that ADH variants, ADH2*1 and ADH3*2, were associated with increased risk for oesophageal cancer, possibly due to the tolerance of the carriers of these alleles to alcohol consumption compared to those with high activity alleles (ADH2*2 and ADH2*3) which are associated with higher production of the unpleasant acetaldehyde intermediate.

Genetic polymorphisms of ADH2 and ALDH2 association with esophageal cancer risk in southwest China

AIM: To evaluate the impact of alcohol dehydrogenase 2 (ADH2) and aldehyde dehydrogenase 2 (ALDH2) polymorphisms on esophageal cancer risk.

METHODS: One hundred and ninety-one esophageal cancer patients and 198 healthy controls from Yanting County were enrolled in this study. ADH2 and ALDH2 genotypes were examined by polymerase-chain-reaction with the confronting-two-pair-primer (PCR-CTPP) method. Unconditional logistic regression was used to calculate the odds ratios (OR) and 95% confidence interval (95% CI).

RESULTS: Both ADH2*1 allele and ALDH2*1/*2 allele showed an increased risk of developing esophageal cancer. The adjusted OR (95% CI) for ADH2*1 allele compared with ADH2*2/*2 was 1.65 (95% CI = 1.02-2.68) and 1.67 (95% CI = 1.02-2.72) for ALDH2*1/*2 compared with ALDH2*1/*1. A significant interaction between ALDH2 and drinking was detected regarding esophageal cancer risk, the OR was 1.83 (95% CI = 1.13-2.95). Furthermore, when compared with ADH2*2/*2 and ALDH2*1/*1 carriers, ADH2*1 and ALDH2*2 carriers showed an elevated risk of developing esophageal cancer among non-alcohol drinkers (OR = 2.46, 95% CI = 0.98-6.14), and a significantly elevated risk of developing esophageal cancer among alcohol drinkers among alcohol drinkers (OR = 9.86, 95% CI = 3.10-31.38).

CONCLUSION: ADH2 and ALDH2 genotypes are associated with esophageal cancer risk. ADH2*1 allele and ALDH2*2 allele carriers have a much higher risk of developing esophageal cancer, especially among alcohol drinkers.

Pueraria lobata (Kudzu root) hangover remedies and acetaldehyde-associated neoplasm risk

Recent introduction of several commercial Kudzu root (Pueraria lobata) containing hangover remedies has occurred in western countries. The available data is reviewed to assess if there are any potential concerns in relationship to the development of neoplasm if these products are used chronically. The herb Pueraria has two components that are used as traditional therapies; Pueraria lobata, the root based herb and Pueraria flos, the flower based herb. Both of these herbal components have different traditional claims and constituents. Pueraria flos, which enhances acetaldehyde removal, is the traditional hangover remedy. Conversely, Pueraria lobata is a known inhibitor of mitochondrial aldehyde dehydrogenase (ALDH2) and increases acetaldehyde. Pueraria lobata is being investigated for use as an aversion therapy for alcoholics due to these characteristics. Pueraria lobata is not a traditional hangover therapy yet has been accepted as the registered active component in many of these hangover products. The risk of development of acetaldehyde pathology, including neoplasms, is associated with genetic polymorphism with enhanced alcohol dehydrogenase (ADH) or reduced ALDH activity leading to increased acetaldehyde levels in the tissues. The chronic usage of Pueraria lobata at times of high ethanol consumption, such as in hangover remedies, may predispose subjects to an increased risk of acetaldehyde-related neoplasm and pathology. The guidelines for Disulfiram, an ALDH2 inhibitor, provide a set of guidelines for use with the herb Pueraria lobata. Pueraria lobata appears to be an inappropriate herb for use in herbal hangover remedies as it is an inhibitor of ALDH2. The recommendations for its use should be similar to those for the ALDH2 inhibitor, Disulfiram.

Genetic polymorphisms and esophageal cancer risk

The aim of this paper is to review and evaluate, in a comprehensive manner, the published data regarding the contribution of genetic polymorphisms to risk of esophageal cancer, including squamous cell carcinoma (SCC) and adenocarcinoma, in humans. All relevant studies available in MEDLINE and published before February 2007 were identified. Studies carried out in humans and that compared esophageal cancer patients with at least 1 standard control group were considered for analysis. One-hundred studies and 3 meta-analyses were identified. Eighty (80%) studies were conducted in Asian countries, particularly China including Taiwan (60 (60%) studies). The most intensively examined genes were those encoding carcinogen metabolic enzymes. The most widely studied gene was GSTM1 (15 studies), followed by ALDH2 (11 studies). ALDH2, MTHFR C677T, CYP1A1 Ile/Val, CYP1A1MspI, CYP2E1, GSTP1, GSTM1 and GSTT1 were examined by meta-analyses and significant relations were found between ALDH2*1*2 and the CYP1A1 Val allele and increased risk of esophageal cancer. In addition, increased risk of esophageal SCC was consistently associated with the ADH2*1*2 and the p53 codon 72 Pro/Pro genotypes. Cohort studies that simultaneously consider multiple genetic and environmental factors possibly involved in esophageal carcinogenesis are needed to ascertain not only the relative contribution of these factors to tumor development but also the contributions of their putative interactions.

Susceptibility to lung cancer and genetic polymorphisms in the alcohol metabolite-related enzymes alcohol dehydrogenase 3, aldehyde dehydrogenase 2, and cytochrome P450 2E1 in the Japanese population

BACKGROUND

It is believed that acetaldehyde plays an important role in alcohol-related carcinogenesis; although current epidemiologic studies have provided inconsistent findings on the association between alcohol consumption and the risk of lung cancer.

METHODS

To clarify the hypothesis that genetic polymorphisms in alcohol-metabolizing enzymes may influence susceptibility to lung cancer, the authors conducted a hospital-based case-control study and examined genetic polymorphisms in the alcohol dehydrogenase 3, aldehyde dehydrogenase 2 (ALDH(2)), and cytochrome P450 2E1 genes in 505 patients with histologically confirmed lung cancer and in a group of 256 noncancer controls who provided complete cigarette and alcohol consumption histories. Genotyping was conducted by polymerase chain reaction-restriction fragment-length polymorphism assay.

RESULTS

A significant association was noted between alcohol consumption and lung cancer risk. Thus, using the median value for the controls as the cut-off point, the odds ratios (OR) for light and heavy drinkers were 1.76 and 1.95, respectively (P for trend = .012), compared with nondrinkers. In addition, there was a significant trend toward increased risk of lung cancer in drinkers with ALDH(2) variant alleles (P for trend <.0001). The adjusted OR for heavy drinkers was 6.15 compared with nondrinkers. Regarding associations between histologic type and genotypes, the ALDH(2) variant allele was significantly less common in patients who had adenocarcinoma compared with controls.

CONCLUSIONS

The current observations suggested a positive association between alcohol consumption and the risk of lung cancer: Drinking may increase the risk, especially among individuals who have the variant ALDH(2) alleles.

Genotoxic effects of alcohol in human peripheral lymphocytes modulated by ADH1B and ALDH2 gene polymorphisms

Ethanol is almost totally broken down by oxidative metabolism in vivo. Ethanol per se is considered to be neither carcinogenic, mutagenic nor genotoxic. However, during the metabolic conversion of ethanol to acetaldehyde and acetate, the organism is exposed to both ethanol and acetaldehyde and therefore ethanol is suspected to be co-carcinogenic. The genetic polymorphisms of alcohol dehydrogenase-2 (ADH1B) and acetaldehyde dehydrogenase-2 (ALDH2) influence the metabolism of alcohol. The ADH1B*1/*1 genotype encodes the low-activity form of ADH1B, and ALDH2*1/*2 and ALDH2*2/*2 genotype encode inactive ALDH2. The aim of this study was to test the hypothesis that polymorphisms of the ADH1B and ALDH2 genes are significantly associated with genotoxicity induced by alcohol drinking, measured using the cytokinesis-block micronucleus (CBMN) assay, an established biomarker of genome instability, in peripheral blood lymphocytes of 286 healthy Japanese men. There was a significant trend for the mean micronuclei (MN) frequency in habitual or moderate drinkers without a smoking habit to increase as the numbers of the *1 allele in ADH1B increased (P=0.039 or P=0.029) and the *2 allele in ALDH2 increased (P=0.019 or P=0.037). A logistic regression analysis showed that the number of subjects with MN frequency levels more than median value of MN (3.0) was significantly higher in the subjects with the ADH1B*1 allele as adjusted estimates (OR 2.08, 95% C.I. 1.24-3.48), when the OR for the subjects with the ADH1B*2/*2 genotype was defined as 1.00. The number of subjects with MN frequency levels more than median value of MN was also significantly higher in the subjects with the ALDH2*2 allele as adjusted estimates (OR 1.79, 95% C.I. 1.04-3.11), when the OR for the subjects with the ALDH2*1/*1 genotype was defined as 1.00. The results of this study have identified important novel associations between ADH1B/ALDH2 polymorphisms and genotoxicity in alcohol drinkers.

Interactive effects of lifetime alcohol consumption and alcohol and aldehyde dehydrogenase polymorphisms on esophageal cancer risks

In our previous study, we found that polymorphisms of alcohol and aldehyde dehydrogenase (ADH1B and ALDH2) are important risks for esophageal squamous cell carcinoma in a Taiwanese population. In this study, we increased the sample size to investigate the modifying effect of lifetime alcohol consumption on the association between ADH1B and ALDH2 genotypes and the risks of esophageal cancer. A multicenter hospital-based case-control study was conducted between August 2000 and June 2004. Three hundred and thirty newly-diagnosed esophageal squamous cell carcinoma patients and 592 controls were recruited from National Taiwan University Hospital in Taipei and Kaohsiung Veterans General Hospital and Kaohsiung Medical University Hospital in Kaohsiung, Taiwan. Controls were matched to the case patients by gender and age within 4 years (case:control = 1:1-4). Polymorphisms of ADH1B and ALDH2 were genotyped by the method of PCR-RFLP. Individuals with ADH1B*1/*1 genotype had a 3.99-fold risk (95% CI = 2.13-7.48) of developing esophageal cancer, compared with those with ADH1B*2/*2 genotype, after adjusted for appropriate covariates. Individuals with ALDH2*1/*2 and ALDH2*2/*2 had 4.99-fold risk (95% CI = 3.11-7.99) and 4.24-fold risk (95% CI = 1.52-11.84), respectively, of developing esophageal cancer, compared with those with ALDH2*1/*1, after adjusted for appropriate covariates. We also found a modifying effect of lifetime alcoholic consumption on the association between genotypes of ADH1B and ALDH2 on esophageal cancer risk. These results suggest that ADH1B and ALDH2 polymorphisms play a pivotal role on esophageal cancer and that the effect of these polymorphisms was modified by the amount of alcohol consumed.

GSTT1, GSTM1 and GSTP1 genetic polymorphisms and interaction with tobacco, alcohol and occupational exposure in esophageal cancer patients from North India

Glutathione S-transferases(GSTs) are detoxification enzymes that provide critical defense against carcinogens. Our hypothesis was that altered frequencies of GST genotypes and environmental exposures might be associated with increased susceptibility for the development of esophageal cancer. A total of 100 esophageal cancer patients and 137 age and gender matched healthy controls were analyzed for GST polymorphisms. Frequencies of GSTT1 null, GSTM1 null and GSTP1 genotypes did not differ between patients and controls. However, a two-fold risk was observed for GSTM1 null genotype in adenocarcinoma (OR(odds ratio) 2.1; 95% CI(confidence intervals)=0.53-8.6). Further, we used a case only design to study gene-environment interactions in esophageal cancer. In patients with smoking habits, GSTM1 null and GSTP1 ile/ile genotype were at higher risk for esophageal cancer (OR 1.5; 95% CI=0.50-4.4 and OR 1.3; 95% CI=0.40-3.5), respectively. A moderate risk for cancer was observed from alcohol usage along with GSTM1 null(OR 1.3; 95% CI=0.50-3.6) and GSTP1 val/val genotypes(OR 1.2; 95% CI=0.20-5.7). Interaction of GST genotypes with occupational exposure did not affect risk for esophageal cancer. These findings suggest that genetic polymorphisms of GSTT1, GSTM1, and GSTP1 are not associated with higher risk of esophageal cancer. However, interaction of smoking or alcohol with GSTM1 null or GSTP1 ile/ile moderately increases the risk for esophageal cancer in North Indian population.