Genetic polymorphisms of alcohol dehydrogense-1B and aldehyde dehydrogenase-2, alcohol flushing, mean corpuscular volume, and aerodigestive tract neoplasia in Japanese drinkers

Alcohol consumption, multiple Lugol-voiding lesions, and field cancerization

The development of multiple squamous cell carcinomas (SCC) in the upper aerodigestive tract, which includes the oral cavity, pharynx, larynx, and esophagus, is explained by field cancerization and is associated with alcohol consumption and cigarette smoking. We reviewed the association between alcohol consumption, multiple Lugol-voiding lesions, and field cancerization, mainly based on the Japan Esophageal Cohort study. The Japan Esophageal Cohort study is a prospective cohort study that enrolled patients with esophageal SCC after endoscopic resection. Enrolled patients received surveillance by gastrointestinal endoscopy every 6 months and surveillance by an otolaryngologist every 12 months. The Japan Esophageal Cohort study showed that esophageal SCC and head and neck SCC that developed after endoscopic resection for esophageal SCC were associated with genetic polymorphisms related to alcohol metabolism. They were also associated with Lugol-voiding lesions grade in the background esophageal mucosa, the score of the health risk appraisal model for predicting the risk of esophageal SCC, macrocytosis, and score on alcohol use disorders identification test. The standardized incidence ratio of head and neck SCC in patients with esophageal SCC after endoscopic resection was extremely high compared to the general population. Drinking and smoking cessation is strongly recommended to reduce the risk of metachronous esophageal SCC after treatment of esophageal SCC. Risk factors for field cancerization provide opportunities for early diagnosis and minimally invasive treatment. Lifestyle guidance of alcohol consumption and cigarette smoking for esophageal precancerous conditions, which are endoscopically visualized as multiple Lugol-voiding lesions, may play a pivotal role in decreasing the incidence and mortality of esophageal SCC.

Usefulness of the aldehyde breath test for predicting metachronous recurrence in patients with esophageal squamous cell carcinoma and hypopharyngeal squamous cell carcinoma

BACKGROUND

The rate of metachronous recurrence after endoscopic submucosal dissection for early-stage esophageal squamous cell carcinoma and hypopharynx squamous cell carcinoma is as high (10-15%). The acetaldehyde breath test may detect acetaldehyde dehydrogenase 2 gene polymorphisms. Therefore, we evaluated its usefulness in assessing metachronous recurrence in patients with esophageal squamous cell carcinoma and hypopharynx squamous cell carcinoma.

METHODS

A total of 76 patients underwent endoscopic submucosal dissection for esophageal squamous cell carcinoma and hypopharynx squamous cell carcinoma and were followed up for at least 3 years (non-recurrence group: 52 patients; recurrence group: 24 patients). The risk factors for carcinogenesis were compared between the recurrence and non-recurrence groups, and the acetaldehyde-to-ethanol ratio was assessed. The cutoff acetaldehyde-to-ethanol ratio that correlated with recurrence was established, and the cumulative recurrence rate was evaluated.

RESULTS

The recurrence group had a higher acetaldehyde-to-ethanol ratio, daily alcohol consumption, and Lugol-voiding lesion grade than the non-recurrence group in the univariate analysis. The cutoff acetaldehyde-to-ethanol ratio for recurrence was 28.1 based on the receiver operating characteristic curve. The multivariate analysis revealed an acetaldehyde-to-ethanol ratio of > 28.1 and a Lugol-voiding lesion grade associated with carcinogenesis. Patients with an acetaldehyde-to-ethanol ratio of ≥ 28.1 had a significantly high recurrence rate using the Kaplan-Meier method.

CONCLUSIONS

The acetaldehyde-to-ethanol ratio detected using the acetaldehyde breath test could be a novel biomarker of metachronous recurrence after endoscopic submucosal dissection in patients with esophageal squamous cell carcinoma and hypopharynx squamous cell carcinoma.

TRIAL REGISTRATION NUMBER

UMIN000040615.

Impact of Alcohol Dehydrogenase 7 Polymorphism and Alcohol Consumption on Risk of Head and Neck Squamous Cell Carcinoma: A Korean Case-Control Study

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is closely associated with alcohol consumption and individual genetic susceptibility, such as single nucleotide polymorphism (SNP) of alcohol dehydrogenase (ADH). This study aimed to investigate the association of ADH7 SNPs with the risk of HNSCC.

METHODS

We analyzed ADH7 rs1573496C>G, rs3737482T>C, rs1154460G>A, and rs284787T>C SNPs in 250 patients with HNSCC and 322 controls in the Korean populations. Genotyping was conducted using the TaqMan assay. Linkage disequilibrium and haplotypes were analyzed.

RESULTS

The odds ratios (OR) and 95% confidence intervals (CI) of the CT and CC genotypes of ADH7 rs3737482T>C were 0.48 (0.29-0.78) and 0.69 (0.49-0.96), indicating a significantly decreased risk. In SNP of rs1154460G>A, the OR and 95% CI of the AA genotype was 1.63 (1.11-2.40), showing a significant increase in the risk. Furthermore, SNPs of ADH7 rs3737482T>C and ADH7 rs1154460G>A exhibit synergistic interactions with alcohol composition on the risk of HNSCC. None of the haplotypes were associated with the risk of HNSCC.

CONCLUSIONS

ADH7 rs3737482T>C and rs1154460G>A SNPs are associated with the risk of development of HNSCC in Koreans. They could serve as molecular biological markers to screen high-risk groups for HNSCC.

Effects of activation of an alcohol metabolic gene, cigarette smoking, and alcohol intake on the incidence of metachronous gastric cancer in patients who underwent endoscopic resection for gastric cancer: A multicenter retrospective pilot study

Background and Aim

Metachronous gastric cancer (GC) frequently occurs in patients who have undergone endoscopic resection (ER) for GC. We evaluated the risk for development of metachronous GC following ER for GC based on genetic polymorphisms for alcohol dehydrogenase-1B (ADH1B) and aldehyde dehydrogenase-2 (ALDH2), as well as alcohol consumption and smoking habits.

Methods

We studied 77 patients who underwent ER for GC (median follow-up of 84 months). Genotyping of ADH1B/ALDH2 was performed using saliva sampling. Histories of alcohol consumption and smoking before and after ER and Helicobacter pylori eradication were documented.

Results

Multivariate analyses revealed that homozygous slow-metabolizing ADH1B (hazard ratio [HR] = 2.38, P < 0.13), heavy smoking (HR = 2.36, P < 0.09), and cigarette smoking after ER (HR = 2.47, P < 0.10) were not independently associated with the risk of secondary GC development. We analyzed the cessation status of the 38 patients who were classified as heavy smokers before ER based on their smoking habits after the ER and divided them into a cessation group (n = 27, non-smokers after ER) and a non-cessation group (n = 11). Cumulative incidence curves of secondary GC in the cessation and non-cessation groups revealed 5-year incidence rates of 19.0% and 45.0%, respectively (P = 0.02).

Conclusion

Continued cigarette smoking, at a high level, may be an important risk factor for the development of metachronous GC. Advice for smoking cessation should be given.

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.

Alcohol metabolism genes and risks of site-specific cancers in Chinese adults: An 11-year prospective study

Two genetic variants that alter alcohol metabolism, ALDH2-rs671 and ADH1B-rs1229984, can modify oesophageal cancer risk associated with alcohol consumption in East Asians, but their associations with other cancers remain uncertain. ALDH2-rs671 G>A and ADH1B-rs1229984 G>A were genotyped in 150 722 adults, enrolled from 10 areas in China during 2004 to 2008. After 11 years' follow-up, 9339 individuals developed cancer. Cox regression was used to estimate hazard ratios (HRs) for site-specific cancers associated with these genotypes, and their potential interactions with alcohol consumption. Overall, the A-allele frequency was 0.21 for ALDH2-rs671 and 0.69 for ADH1B-rs1229984, with A-alleles strongly associated with lower alcohol consumption. Among men, ALDH2-rs671 AA genotype was associated with HR of 0.69 (95% confidence interval: 0.53-0.90) for IARC alcohol-related cancers (n = 1900), compared to GG genotype. For ADH1B-rs1229984, the HRs of AG and AA vs GG genotype were 0.80 (0.69-0.93) and 0.75 (0.64-0.87) for IARC alcohol-related cancers, 0.61 (0.39-0.96) and 0.61 (0.39-0.94) for head and neck cancer (n = 196) and 0.68 (0.53-0.88) and 0.60 (0.46-0.78) for oesophageal cancer (n = 546). There were no significant associations of these genotypes with risks of liver (n = 651), colorectal (n = 556), stomach (n = 725) or lung (n = 1135) cancers. Among male drinkers, the risks associated with higher alcohol consumption were greater among ALDH2-rs671 AG than GG carriers for head and neck, oesophageal and lung cancers (Pinteraction  < .02). Among women, only 2% drank alcohol regularly, with no comparable associations observed between genotype and cancer. These findings support the causal effects of alcohol consumption on upper aerodigestive tract cancers, with ALDH2-rs671 AG genotype further exacerbating the risks.

Alcohol dehydrogenase expression patterns in normal prostate, benign prostatic hyperplasia, and prostatic adenocarcinoma in African American and Caucasian men

BACKGROUND

In situ metabolism of ethanol by alcohol dehydrogenases (ADHs) contributes to oxidative damage of cells and DNA and has been linked to carcinogenesis in numerous epithelial tissues. The goal of this study was to determine expression patterns of ADH1 and ADH7 isozymes in normal, hyperplastic (benign prostatic hyperplasia [BPH]) and neoplastic (prostate cancer [PCa]) prostate. Furthermore, racial differences in ADH expression between African Americans and Caucasians were investigated.

METHODS

ADH expression patterns were characterized by density analysis of ADH immunohistochemistry (n = 21) and real-time RT-PCR of total RNAs by laser-capture microdissection (n = 10) and whole tissue formalin-fixed paraffin embedded prostate biopsies (n = 63).

RESULTS

ADH protein is found in normal prostate and is primarily associated with glandular epithelium. Transcripts of ADH1B are suppressed in PCa compared to BPH (p = 0.0095). Racial differences in ADH7 transcripts exist between African American and Caucasian men. A total of 57.6% of biopsies from African American prostates have detectable ADH7 messenger RNA (mRNA) transcripts compared to the 13.3% of Caucasian prostate biopsies with detectable transcripts (p = 0.0005). This increased frequency of detection contributes to higher mean ADH7 mRNA transcript levels in African Americans (p = 0.001).

CONCLUSIONS

To our knowledge this study is the first to report downregulation of ADH1B in neoplastic prostate at the transcriptional level, suggesting protective regulatory functions. ADH7 transcripts were not detectable in all samples and was found in higher frequency and amount in our African American samples. Racial differences in ADH7 within the prostate is a novel finding and should be investigated further.

Alcohol Consumption, ALDH2 Polymorphism as Risk Factors for Upper Aerodigestive Tract Cancer Progression and Prognosis

The upper aerodigestive tract (UADT) is highly susceptible to multiple primary cancers originated from squamous epithelia and constitutes a field of cancerization. Patients with head and neck cancer (head and neck squamous cell carcinoma, HNSCC) are at high risk of developing multiple cancers in the esophagus (esophageal squamous cell carcinoma, ESCC). Conversely, esophageal cancer patients are prone to develop multiple primary tumors in the head and neck region. The East Asian-specific dysfunctional ALDH2*2 missense mutation is a genetic risk factor for UADT cancer. It is not only associated with increased incidences of UADT cancer, but is also implicated in faster cancer progression and poorer prognosis. Alcohol use is a major lifestyle risk factor which causes UADT cancer among ALDH2*2 carriers. The accumulation of the immediate metabolite of alcohol, acetaldehyde, is likely the genotoxic agents that is involved in the process of tumorigenesis. This review summarizes recent publications on the risk and association of ALDH2*2 mutation, alcohol consumption in synchronous, metachronous UADT cancer. Possible molecular mechanisms involved in cancer initiation, progress and prognosis are discussed. The review also highlights a need for precision medicine-based preventive and therapeutic strategies by integrating lifestyle and genetic risk factors, such as alcohol consumption, genotypes of the alcohol metabolizing genes, ADH1B and ALDH2, into a risk assessment model for better screening, surveillance and treatment outcome.

Acetaldehyde breath test as a cancer risk marker in patients with esophageal and hypopharyngeal squamous cell carcinoma

Patients with inactive acetaldehyde dehydrogenase 2 (ALDH2) are at high risk for esophageal squamous cell carcinoma (ESCC) and hypopharyngeal squamous cell carcinoma (HPSCC). The acetaldehyde breath test (ABT) may demonstrate ALDH2 gene polymorphisms. We evaluated the usefulness of the ABT in patients with ESCC and HPSCC. The squamous cell carcinoma (SCC) group consisted of 100 patients who were treated with endoscopic submucosal dissection (ESD) for ESCC or HPSCC, and the control group (HC) consisted of 275 healthy subjects. The SCC group comprised the “single subgroup” (n = 63), in which a single lesion was initially treated with ESD, and the “multiple subgroup” (n = 31), in which multiple lesions were initially treated with ESD. First, we compared the groups’ risk factors for carcinogenesis and measured the acetaldehyde-to-ethanol (A/E) ratio. Then we tested the groups’ differences in the abovementioned carcinogenic risk factors. We found that the proportion of individuals in the SCC group with inactive ALDH2 (A/E ratio ≥ 23.3) was significantly higher than that in the HC group (p = 0.035), as was the A/E ratio (p < 0.001). Also, the proportion of individuals with inactive ALDH2 in the multiple subgroup was significantly higher than that in single subgroup (p = 0.015), as was the A/E ratio (p = 0.008). In conclusion, ABT may be a potential screening tool for detecting people at risk of ESCC and HPSCC. In addition, it could be a useful tool in detecting patients at risk of multiple or double carcinomas among patients with ESCC and HPSCC.

Trial registration: Trial Registration number: UMIN000040615 [https://rctportal.niph.go.jp/en/detail?trial_id=UMIN000040615], Data of Registration: 01 46 June 2020, retrospectively registered.

Clinical Importance of Mean Corpuscular Volume as a Prognostic Marker After Esophagectomy for Esophageal Cancer: A Retrospective Study

OBJECTIVE

To elucidate the clinical value of mean corpuscular volume (MCV) for prognostic prediction in patients with esophageal cancer who underwent radical esophagectomy.

BACKGROUND

High MCV is suggested to be relevant to the incidence and prognosis of several malignancies. However, few studies investigating the correlation between MCV and survival outcome of esophageal cancer have been conducted.

METHODS

This study included 570 patients with esophageal cancer who underwent radical esophagectomy between April, 2005 and December, 2017. Patients were divided into 2 groups according to the standard value of pretreatment MCV: normal (83-99 fL) and high (>99 fL) groups. Clinical backgrounds, short-term outcomes, and prognostic outcomes postesophagectomy were retrospectively compared between the groups.

RESULTS

Of all patients, 410 (71.9%) had normal MCV, and 160 (28.1%) had high MCV. High MCV was significantly associated with lower body mass index, higher frequency of habitual alcohol and tobacco use, and higher incidence of multiple primary malignancies other than esophageal cancer. High MCV also correlated with higher incidence of postoperative morbidity of the Clavien-Dindo classification ≥II and pulmonary morbidity. Overall survival was significantly worse in patients with high MCV. Multivariate analysis suggested that high MCV was an independent risk factor for worse survival outcome (hazard ratio 1.54, 95% confidence interval 1.098-2.151, P = 0.012).

CONCLUSIONS

Patients with high MCV have various disadvantages in clinical background that can adversely affect both short-term and long-term outcomes after esophagectomy. MCV can become a predictive marker to estimate survival outcome after esophagectomy for esophageal cancer.

Contributing Roles of CYP2E1 and Other Cytochrome P450 Isoforms in Alcohol-Related Tissue Injury and Carcinogenesis

The purpose of this review is to briefly summarize the roles of alcohol (ethanol) and related compounds in promoting cancer and inflammatory injury in many tissues. Long-term chronic heavy alcohol exposure is known to increase the chances of inflammation, oxidative DNA damage, and cancer development in many organs. The rates of alcohol-mediated organ damage and cancer risks are significantly elevated in the presence of co-morbidity factors such as poor nutrition, unhealthy diets, smoking, infection with bacteria or viruses, and exposure to pro-carcinogens. Chronic ingestion of alcohol and its metabolite acetaldehyde may initiate and/or promote the development of cancer in the liver, oral cavity, esophagus, stomach, gastrointestinal tract, pancreas, prostate, and female breast. In this chapter, we summarize the important roles of ethanol/acetaldehyde in promoting inflammatory injury and carcinogenesis in several tissues. We also review the updated roles of the ethanol-inducible cytochrome P450-2E1 (CYP2E1) and other cytochrome P450 isozymes in the metabolism of various potentially toxic substrates, and consequent toxicities, including carcinogenesis in different tissues. We also briefly describe the potential implications of endogenous ethanol produced by gut bacteria, as frequently observed in the experimental models and patients of nonalcoholic fatty liver disease, in promoting DNA mutation and cancer development in the liver and other tissues, including the gastrointestinal tract.

Genetic variants of alcohol-metabolizing enzymes in Brugada syndrome: Insights into syncope after drinking alcohol

BACKGROUND

Patients with Brugada syndrome (BrS) are known to have arrhythmic events after alcohol drinking and are recommended to avoid its excessive intake. Mechanisms underlying the alcohol-induced cardiac events are however unknown. This study aimed to test the hypothesis whether activity of alcohol-metabolizing enzymes determines fatal arrhythmic events after drinking alcohol.

METHODS

A total of 198 Japanese patients with BrS were enrolled in this study. These patients were classified into symptomatic (n = 90) and asymptomatic (n = 108) groups. The former was divided into an alcohol-related group (syncope after alcohol drinking, n = 16) and an alcohol-unrelated group (n = 74). Polymerase chain reaction was performed to determine genetic variants of genes encoding alcohol dehydrogenase 1B (ADH1B) and aldehyde dehydrogenase 2 (ALDH2).

RESULTS

The genotype distribution for ALDH2 was not significantly different between symptomatic and asymptomatic groups and between alcohol-related and alcohol-unrelated groups. The genotype distribution for ADH1B was not significantly different between symptomatic and asymptomatic groups, but the genotype ADH1B His/His was significantly more prevalent in the alcohol-related group than in the alcohol-unrelated group (81.3% vs 50%, P = .023). In multivariate logistic regression analysis, the genotype of ADH1B His/His was independently associated with syncope after alcohol drinking (odds ratio, 5.746; 95% confidence interval, 1.580-28.421; P = .007).

CONCLUSIONS

Arrhythmic events after alcohol drinking was associated with enhanced activity of alcohol-metabolizing enzyme ADH1B in our cohort of BrS. Therefore, the lifestyle change to avoid the excessive alcohol intake deserves attention.

Risk assessment of metachronous squamous cell carcinoma after endoscopic resection for esophageal carcinoma based on the genetic polymorphisms of alcoholdehydrogense-1B aldehyde dehydrogenase-2: temperance reduces the risk

BACKGROUND

Metachronous multiple squamous cell carcinoma (SCC) of the esophagus and the head and neck is commonly observed in patients who have previously undergone endoscopic resection (ER) for SCC of the esophagus (ESCC). We evaluated the risk for developing metachronous SCC following ER for ESCC based on the genetic polymorphisms for alcohol dehydrogenase-1B (ADH1B) and aldehyde dehydrogenase-2 (ALDH2) as well as the alcohol consumption and smoking habits.

METHODS

We studied 158 patients who underwent ER for ESCC (median follow-up 80 months). Genotyping of ADH1B/ALDH2 was performed using saliva sampling. The alcohol consumption and smoking histories of the patients before and after the ER were documented.

RESULTS

Multivariate analyses revealed that inactive heterozygous ALDH2 [hazard ratio (HR) 2.25] and alcohol consumption after ER (HR 1.94) were independently associated with the risk of developing secondary SCC. Moreover, inactive heterozygous ALDH2 (HR 4.39) and alcohol consumption after the ER (HR 2.82) were independently associated with the risk of a third SCC. We analyzed 110 patients who had a history of moderate or heavy alcohol consumption before the ER. The 3-year cumulative incidence rates of secondary SCC in the temperance (n = 65) and non-temperance groups (n = 45) were 14.0 and 42.1% (p = 0.0002). Further, the 5-year cumulative incidence rates of a third SCC in the temperance and non-temperance groups were 0 and 15.6% (p = 0.0011), respectively. In addition, the 7-year cumulative incidence rates of a fourth SCC in the temperance and non-temperance groups were 0 and 15.3% (p = 0.0015), respectively.

CONCLUSIONS

Continued alcohol consumption is an important risk factor for the onset of metachronous SCC and is a risk factor for the third and subsequent SCCs. Strict advice in favor of temperance is crucial.

Validation of Alcohol Flushing Questionnaires in Determining Inactive Aldehyde Dehydrogenase-2 and Its Clinical Implication in Alcohol-Related Diseases

BACKGROUND

Our aim was to validate alcohol flushing questionnaires in detecting inactive ALDH2 (ALDH2*1/*2 or ALDH2*2/*2).

METHODS

Two study sets were established; in study set 1, 210 healthy male subjects (age 22 to 59 years) were enrolled; in study set 2, 756 subjects were enrolled who received esophagogastroduodenoscopy to evaluate their dyspeptic symptoms or as part of a gastric cancer screening program. Subjects in study sets 1 and 2 completed the modified alcohol flushing questionnaires of Yokoyama and colleagues (, ). Polymerase chain reaction-restriction fragment length polymorphism method was used to determine ALDH2 genotype.

RESULTS

In study set 1, 29.0% (61 of 210) had inactive ALDH2. The sensitivity and specificity of the modified alcohol flushing questionnaire for detecting inactive ALDH2 were 95.1 and 76.5%, respectively. Drinking problems negatively correlated with positive alcohol flushing response and inactive ALDH2 (all p-values < 0.05). In study set 2, the sensitivity and specificity of the alcohol flushing questionnaire for detecting inactive ALDH2 were 78.9 and 82.1%, respectively. Interestingly, drinking ≥7 units/wk in men or ≥3.5 units/wk in women significantly increased the risk of benign gastric ulcer (BGU) among positive alcohol flushers (odds ratio, 8.97; 95% confidence interval, 1.38 to 58.30), but not among negative alcohol flushers.

CONCLUSIONS

Simple flushing questionnaires may be administered to the Korean population as a screening tool in detecting individuals who carry inactive ALDH2. Alcohol flushing response negatively correlates with drinking problems and can modify the risk for BGU by alcohol intake.

Factors associated with the high prevalence of oesophageal cancer in Western Kenya: a review

Oesophageal carcinoma (OC) is highly prevalent in Western Kenya especially among the members of the Kalenjin community who reside in the Northern and Southern areas of the Rift Valley. Previous authors have suggested potential association of environmental and genetic risk factors with this high prevalence. The environmental factors that have been suggested include contamination of food by mycotoxins and/or pesticides, consumption of traditional alcohol (locally referred to “Busaa” and “Chan’gaa”), use of fermented milk (“Mursik”), poor diet, tobacco use and genetic predisposition. The aim of this paper is to critically examine the potential contribution of each of the factors that have been postulated to be associated with the high prevalence of the disease in order to establish the most likely cause. We have done this by analyzing the trends, characteristics and behaviours that are specifically unique in the region, and corroborated this with the available literature.

From our findings, the most plausible cause of the high incidence of OC among the Kalenjin community is mycotoxins, particularly fumonisins from the food chain resulting from poor handling of cereals; particularly maize combined with traditional alcohol laced with the toxins interacting synergistically with other high-risk factors such as dietary deficiencies associated alcoholism and viral infections, especially HPV. Urgent mitigating strategies should be developed in order to minimize the levels of mycotoxins in the food chain.

Molecular Mechanisms of Acetaldehyde-Mediated Carcinogenesis in Squamous Epithelium

Acetaldehyde is a highly reactive compound that causes various forms of damage to DNA, including DNA adducts, single- and/or double-strand breaks (DSBs), point mutations, sister chromatid exchanges (SCEs), and DNA-DNA cross-links. Among these, DNA adducts such as N²-ethylidene-2'-deoxyguanosine, N²-ethyl-2'-deoxyguanosine, N²-propano-2'-deoxyguanosine, and N²-etheno-2'-deoxyguanosine are central to acetaldehyde-mediated DNA damage because they are associated with the induction of DNA mutations, DNA-DNA cross-links, DSBs, and SCEs. Acetaldehyde is produced endogenously by alcohol metabolism and is catalyzed by aldehyde dehydrogenase 2 (ALDH2). Alcohol consumption increases blood and salivary acetaldehyde levels, especially in individuals with ALDH2 polymorphisms, which are highly associated with the risk of squamous cell carcinomas in the upper aerodigestive tract. Based on extensive epidemiological evidence, the International Agency for Research on Cancer defined acetaldehyde associated with the consumption of alcoholic beverages as a "group 1 carcinogen" (definite carcinogen) for the esophagus and/or head and neck. In this article, we review recent advances from studies of acetaldehyde-mediated carcinogenesis in the squamous epithelium, focusing especially on acetaldehyde-mediated DNA adducts. We also give attention to research on acetaldehyde-mediated DNA repair pathways such as the Fanconi anemia pathway and refer to our studies on the prevention of acetaldehyde-mediated DNA damage.

Frequent aberrant p53 and Fhit expression in endoscopically resected superficial hypopharyngeal cancer and esophageal cancer

In the last decade, the incidence rate of detection rate of superficial head, neck and esophageal squamous cell carcinomas has increased with the development of endoscopic imaging techniques. These cancers are thought to arise independently subsequent to tissue exposure to a common carcinogen e.g. alcohol or tobacco. This phenomenon has been termed field cancerization. To determine the molecular background of the development of hypopharyngeal squamous cell carcinomas (HPSCCs) and double esophageal squamous cell carcinomas (DESCCs), the present study immunohistochemically assessed tumor-related protein expression [p53, Fhit (fragile histidine triad), E-cadherin and activation-induced cytidine deaminase (AID)], and subsequently determined the correlation between protein expression and clinicopathological data. Tumor specimens of 9 HPSCCs and 9 DESCCs were endoscopically obtained from 8 patients with HPSCC. The 9 DESCCs, including 5 synchronous and 4 metachronous lesions, were all obtained from four patients with HPSCC. The overexpression of p53 and loss of Fhit expression was immunohistochemically detected in 8 (88.9%) and 8 (88.9%) of the 9 HPSCCs and in 8 (88.9%) and 8 (88.9%) of the 9 DESCCs, respectively, which demonstrated the high frequency of such expression. Additionally, 7 out of 9 HPSCCs, and 7 out of 9 DESCCs demonstrated aberrant expression of p53 and Fhit. The rate of aberrant AID and E-cadherin expression was 67 and 44% in HPSCCs and 44 and 44% in DESCC, respectively. These results suggested that aberrant p53 and Fhit expression was involved in the development of HPSCC and their DESCC, and that their expression may be used for the prediction of DESCC development in patients with HPSCC, thereby acting as a biomarker of field cancerization.

Roles of defective ALDH2 polymorphism on liver protection and cancer development

Because serum transaminases elevate alcohol dose dependently as a consequence of liver injury, they serve as useful biological markers of excessive drinking. However, these markers are inadequate in individuals with a defective allele of the aldehyde dehydrogenase 2 gene, ALDH2*2, because they show a different correlation with the amount of ethanol. For example, the serum alanine aminotransferase (ALT) level could become even lower than the baseline after alcohol intake in ALDH2*2 carriers. In fact, multiple studies suggest that ALDH2*2 is a hepato-protective factor in healthy individuals. Importantly, excessive drinking is particularly dangerous in carriers of ALDH2*2 because the risk of alcohol-related cancer is much higher than that for ALDH2*1/*1 carriers. Without recognizing the genotype interaction on serum transaminase, the opportunity to warn people about potential cancer risks is missed owing to incorrect interpretation. This is particularly important in East Asian countries where approximately half of the population carries the ALDH2*2 allele. To date, the mechanism of liver protection from ethanol load in individuals with ALDH2*2 has not been fully elucidated. However, some reasonable mechanisms have been suggested by experimental studies, including remodelling of detoxifying systems. Further studies to uncover the whole mechanism are anticipated.

Heme oxygenase 1 protects ethanol-administered liver tissue in Aldh2 knockout mice

A genetic polymorphism of the aldehyde dehydrogenase 2 (​ALDH2) gene, ALDH2*2, encodes an enzymatically defective ALDH2 protein. Recent epidemiological studies suggest that possessing ALDH2*2 is a protective factor for liver tissue in healthy individuals, although these studies lack a mechanistic explanation. Our animal studies have shown the same trend: levels of serum alanine transaminase (ALT), hepatic malondialdehyde (MDA), and hepatic tumor necrosis factor alpha (TNF-α) were lower in Aldh2 knockout (Aldh2(-/-)) mice than in wild-type (Aldh2(+/+)) mice after ethanol administration. To propose a mechanistic hypothesis, residual liver specimens from the previous experiment were analyzed. An anti-oxidative protein, heme oxygenase 1 (HO-1), and an oxidative stress-producing protein, cytochrome P450 2E1 (CYP2E1), were detected at higher levels in Aldh2(-/-) mice than in Aldh2(+/+) mice, regardless of ethanol treatment. Other oxidative stress-related proteins and inflammatory cytokines did not show such a significant difference. To conclude, we propose a protective role of HO-1 in individuals with A​LDH2*2. Our continued studies support the epidemiological finding that possession of ALDH2*2 is a protective factor in the liver of the healthy individual.

[Fundamental Properties of Aldehyde Dehydrogenase 2 (ALDH2) and the Importance of the ALDH2 Polymorphism]

Human aldehyde dehydrogenase 2 (ALDH2) is a 56 kDa mitochondrial protein that forms homodimers through hydrogen bonding interactions between the Glu487 and Arg475 residues of two ALDH2 proteins. Two ALDH2 homodimers can interact to form an ALDH2 tetramer. ALDH2 is widely distributed throughout the organs of the body. In addition to its dehydrogenase activity, ALDH2 also exhibits esterase and reductase activities, with the main substrates for these three activities being aldehydes, 4-nitrophenyl acetate and nitroglycerin, respectively. ALDH2 can be readily inhibited by a wide variety of endogenous and exogenous chemicals, but the induction or activation of this enzyme remains unlikely. The polymorphism of ALDH2 to the corresponding ALDH2*2 variant results in a severe deficiency in ALDH2 activity, and this particular polymorphism is prevalent among people of Mongoloid descent. It seems reasonable to expect that people with the ALDH2*2 variant would be more vulnerable to stress and diseases because ALDH2 defends the human body against toxic aldehydes. However, it has been suggested that people with the ALDH2*2 variant are protected by alternative stress-defending systems. The ALDH2*2 variant has been reported to be associated with many different kinds of diseases, although the mechanisms underlying these associations have not yet been elucidated. ALDH2 polymorphism has a significant impact on human health; further studies are therefore required to determine the practical implications of this polymorphism in the fields of preventive and clinical medicine.

Elevated red cell distribution width contributes to a poor prognosis in patients with esophageal carcinoma

BACKGROUND

The red cell distribution width (RDW) has also been reported to reliably reflect the inflammation and nutrition status and predict the prognosis across several types of cancer, however, the prognostic value of RDW in esophageal carcinoma has seldom been studied.

METHODS

A retrospective study was performed to assess the prognostic value of RDW in patients with esophageal carcinoma by the Kaplan-Meier analysis and multivariate Cox regression proportional hazard model. All enrolled patients were divided into high RDW group (≧15%) and low RDW group (<15%) according to the detected RDW values.

RESULTS

Clinical and laboratory data from a total of 179 patients with esophageal carcinoma were retrieved. With a median follow-up of 21months, the high RDW group exhibited a shorter disease-free survival (DFS) (p<0.001) and an unfavorable overall survival (OS) (p<0.001) in the univariate analysis. The multivariate analysis revealed that elevated RDW at diagnosis was an independent prognostic factor for shorter PFS (p=0.043, HR=1.907, 95% CI=1.020-3.565) and poor OS (p=0.042, HR=1.895, 95% CI=1.023-3.508) after adjustment with other cancer-related prognostic factors.

CONCLUSION

The present study suggests that elevated preoperative RDW(≧15%) at the diagnosis may independently predict poorer disease-free and overall survival among patients with esophageal carcinoma.