Alcohol and cancer

DNA methyltransferase and alcohol dehydrogenase: gene-nutrient interactions in relation to risk of colorectal polyps

Disturbances in DNA methylation are a characteristic of colorectal carcinogenesis. Folate-mediated one-carbon metabolism is essential for providing one-carbon groups for DNA methylation via DNA methyltransferases (DNMTs). Alcohol, a folate antagonist, could adversely affect one-carbon metabolism. In a case-control study of colorectal polyps, we evaluated three single nucleotide polymorphisms (-149C>T, -283T>C, -579G>T) in the promoter region of the DNMT3b gene, and a functional polymorphism in the coding region of the alcohol dehydrogenase ADH1C gene, ADH1C *2. Cases had a first diagnosis of colorectal adenomatous (n = 530) or hyperplastic (n = 202) polyps at the time of colonoscopy, whereas controls were polyp-free (n = 649). Multivariate logistic regression analysis was used to estimate odds ratios (OR) and corresponding 95% confidence intervals (CI). There were no significant main associations between the DNMT3b or ADH1C polymorphisms and polyp risk. However, DNMT3b -149TT was associated with an increase in adenoma risk among individuals with low folate and methionine intake (OR, 2.00; 95% CI, 1.06-3.78, P interaction = 0.10). The ADH1C *2/*2 genotype was associated with a possibly elevated risk for adenomatous polyps among individuals who consumed >26 g of alcohol/d (OR, 1.95; 95% CI, 0.60-6.30), whereas individuals who were wild-type for ADH1C were not at increased risk of adenoma (P interaction = 0.01). These gene-diet interactions suggest that polymorphisms relevant to DNA methylation or alcohol metabolism may play a role in colorectal carcinogenesis in conjunction with a high-risk diet.

Interrelation of saturated fat, trans fat, alcohol intake, and subclinical atherosclerosis

BACKGROUND

Intake of saturated fat, trans fat, and alcohol alter cardiovascular disease risk, but their effect on subclinical atherosclerosis remains understudied.

OBJECTIVE

The objective was to examine and quantify the interrelation of saturated fat, trans fat, alcohol intake, and mean carotid artery intimal medial thickness (IMT).

DESIGN

We conducted a population-based, cross-sectional study among 620 persons of Aboriginal, South Asian, Chinese, or European origin aged 35-75 y, who had lived in Canada for >or=5 y. Mean IMT was calculated from 6 well-defined segments of the right and left carotid arteries with standardized B-mode ultrasound, and saturated fat, trans fat, and alcohol intakes were measured with validated food-frequency questionnaires.

RESULTS

For every 10-g/d increase in saturated fat intake, IMT was 0.03 mm higher (P=0.01) after multivariate adjustment. A 1-g/d higher intake of trans fat was associated with a 0.03-mm higher IMT (P=0.02) after multivariate adjustment. The ratio of polyunsaturated to saturated fat (P:S) was inversely associated with IMT after multivariate adjustment (change in IMT: -0.06 mm; P<0.01). Saturated and trans fat intakes were independently associated with IMT thickness (change in IMT: 0.03 mm; P<0.01 and 0.02, respectively; P for interaction=0.01). Polyunsaturated, monounsaturated, cholesterol, and total fat intakes were unrelated to IMT. The relation between saturated fat intake and IMT strengthened (beta=0.0066, P<0.001) in persons who never or rarely consumed alcohol as compared with moderate or heavy drinkers (beta=0.0001, P=0.79, P for interaction=0.01).

CONCLUSION

Higher habitual intakes of saturated and trans fats are independently associated with increased subclinical atherosclerosis, and alcohol intake may attenuate the relation between saturated fat and subclinical atherosclerosis.

Increase of hypophyseal hormone levels in male head and neck cancer patients

Head and neck squamous cell carcinoma (HNSCC) develops in at least 80% of cases in men with a history of smoking and heavy alcohol consumption, still it is only diagnosed in a small proportion of alcoholics. Endocrine milieu is an important factor in carcinogenesis and prognosis of several cancer types. The aim of our study was to investigate sex steroid and hypophyseal hormone status of male HNSCC patients in comparison to healthy volunteers and to patients with alcoholic liver disease, to determine possible hormonal alterations characteristic of cancer. Liver function (GGT level), and serum levels of gonadotropic hormones (FSH, LH, prolactin), sex steroids (estradiol, progesterone, testosterone) and sex hormone-binding globulin (SHBG) were compared in 130 male HNSCC patients, 54 patients with alcoholic liver disease but no known cancer, and 56 healthy controls. We found abnormal values of liver function in both HNSCC patients and alcoholics compared to healthy controls, suggesting the presence of alcoholic liver disease in the former group as well. On the other hand, a significant elevation in the level of DHEA, FSH and LH was observed in cancer patients exclusively. As a conclusion, abnormal alterations in sex steroid hormone levels can frequently be found in HNSCC patients, which may be caused in part by the alcoholic liver damage accompanying the disease. The significant increase in FSH and LH serum levels, observed only in the cancer patients, indicates that these hormones may play a role in the development and/or progression of HNSCC.

Utilization and cost of mental health, substance abuse, and medical services among at-risk drinkers

The objective of this research was to examine whether users of mental health or substance abuse (MH/SA) services incurred greater costs for non-MH/SA services than nonusers of MH/SA services. Two years of health care utilization data were collected on 443 at-risk drinkers from six southern U.S. states. We then examined predictors of using MH/SA services and costs associated with non-MH/SA services. The results showed that use of MH/SA services was associated with female gender, military service, health insurance, and not being employed full-time. Unadjusted analyses indicated that non-MH/SA service costs were significantly higher among MH/SA service users than nonusers. However, this association did not endure in multivariable models. In fact, emergency department costs were significantly lower among MH/SA users. It is commonly assumed that users of MH/SA services are also heavy users of other medical services. Through multivariable models, this study found that overall costs of non-MH/SA services were similar between users and nonusers of MH/SA services.

Phosphatidylethanol accumulation promotes intestinal hyperplasia by inducing ZONAB-mediated cell density increase in response to chronic ethanol exposure

Chronic alcohol consumption is associated with increased risk of gastrointestinal cancer. High concentrations of ethanol trigger mucosal hyperregeneration, disrupt cell adhesion, and increase the sensitivity to carcinogens. Most of these effects are thought to be mediated by acetaldehyde, a genotoxic metabolite produced from ethanol by alcohol dehydrogenases. Here, we studied the role of low ethanol concentrations, more likely to mimic those found in the intestine in vivo, and used intestinal cells lacking alcohol dehydrogenase to identify the acetaldehyde-independent biological effects of ethanol. Under these conditions, ethanol did not stimulate the proliferation of nonconfluent cells, but significantly increased maximal cell density. Incorporation of phosphatidylethanol, produced from ethanol by phospholipase D, was instrumental to this effect. Phosphatidylethanol accumulation induced claudin-1 endocytosis and disrupted the claudin-1/ZO-1 association. The resulting nuclear translocation of ZONAB was shown to mediate the cell density increase in ethanol-treated cells. In vivo, incorporation of phosphatidylethanol and nuclear translocation of ZONAB correlated with increased proliferation in the colonic epithelium of ethanol-fed mice and in adenomas of chronic alcoholics. Our results show that phosphatidylethanol accumulation after chronic ethanol exposure disrupts signals that normally restrict proliferation in highly confluent intestinal cells, thus facilitating abnormal intestinal cell proliferation.

Lifetime and baseline alcohol intake and risk of colon and rectal cancers in the European prospective investigation into cancer and nutrition (EPIC)

Alcohol consumption may be associated with risk of colorectal cancer (CRC), but the epidemiological evidence for an association with specific anatomical subsites, types of alcoholic beverages and current vs. lifetime alcohol intake is inconsistent. Within the European Prospective Investigation into Cancer and Nutrition (EPIC), 478,732 study subjects free of cancer at enrolment between 1992 and 2000 were followed up for an average of 6.2 years, during which 1,833 CRC cases were observed. Detailed information on consumption of alcoholic beverages at baseline (all cases) and during lifetime (1,447 CRC cases, 69% of the cohort) was collected from questionnaires. Cox proportional hazard models were used to examine the alcohol-CRC association. After adjustment for potential confounding factors, lifetime alcohol intake was significantly positively associated to CRC risk (hazard ratio, HR=1.08, 95%CI=1.04-1.12 for 15 g/day increase), with higher cancer risks observed in the rectum (HR=1.12, 95%CI=1.06-1.18) than distal colon (HR=1.08, 95%CI=1.01-1.16), and proximal colon (HR=1.02, 95%CI=0.92-1.12). Similar results were observed for baseline alcohol intake. When assessed by alcoholic beverages at baseline, the CRC risk for beer (HR=1.38, 95%CI=1.08-1.77 for 20-39.9 vs. 0.1-2.9 g/day) was higher than wine (HR=1.21, 95%CI=1.02-1.44), although the two risk estimates were not significantly different from each other. Higher HRs for baseline alcohol were observed for low levels of folate intake (1.13, 95%CI=1.06-1.20 for 15 g/day increase) compared to high folate intake (1.03, 95%CI=0.98-1.09). In this large European cohort, both lifetime and baseline alcohol consumption increase colon and rectum cancer risk, with more apparent risk increases for alcohol intakes greater than 30 g/day.

Molecular mechanisms of alcohol-mediated carcinogenesis

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

Socioeconomic inequalities in alcohol related cancer mortality among men: to what extent do they differ between Western European populations?

We aim to study socioeconomic inequalities in alcohol related cancers mortality [upper aerodigestive tract (UADT) (oral cavity, pharynx, larynx, oesophagus and liver)] in men and to investigate whether the contribution of these cancers to socioeconomic inequalities in cancer mortality differs within Western Europe. We used longitudinal mortality datasets, including causes of death. Data were collected during the 1990s among men aged 30-74 years in 13 European populations [Madrid, the Basque region, Barcelona, Turin, Switzerland (German and Latin part), France, Belgium (Walloon and Flemish part, Brussels), Norway, Sweden, Finland]. Socioeconomic status was measured using the educational level declared at the census at the beginning of the follow-up period. We conducted Poisson regression analyses and used both relative [Relative index of inequality (RII)] and absolute (mortality rates difference) measures of inequality. For UADT cancers, the RII's were above 3.5 in France, Switzerland (both parts) and Turin whereas for liver cancer they were the highest (around 2.5) in Madrid, France and Turin. The contribution of alcohol related cancer to socioeconomic inequalities in cancer mortality was 29-36% in France and the Spanish populations, 17-23% in Switzerland and Turin, and 5-15% in Belgium and the Nordic countries. We did not observe any correlation between mortality rates differences for lung and UADT cancers, confirming that the pattern found for UADT cancers is not only due to smoking. This study suggests that alcohol use substantially influences socioeconomic inequalities in male cancer mortality in France, Spain and Switzerland but not in the Nordic countries and nor in Belgium.

In vitro Benzo[a]pyrene Diol Epoxide–Induced DNA Adducts and Risk of Squamous Cell Carcinoma of Head and Neck

In this large confirmatory study of 803 patients with squamous cell carcinoma of head and neck (SCCHN) and 839 controls frequency matched by age, sex, and ethnicity, we further examined potential predictors of benzo[a]pyrene diol epoxide (BPDE)-induced adduct levels and their associations with SCCHN risk. BPDE-DNA adduct levels were determined by the (32)P-postlabeling method in peripheral lymphocytes after in vitro challenged by BPDE. We also genotyped for GSTM1 null, GSTT1 null, GSTP1 Ile(105)Val, and GSTP1 Ala(114)Val. Potential predictors of BPDE-DNA adducts were evaluated by stratification and multivariate linear regression analyses and the association between adduct levels and SCCHN risk by multivariate logistic regression analyses. We found that mean BPDE-DNA adduct levels (the relative adduct labeling x 10(7) +/- SD) were significantly higher in cases (77.6 +/- 111.8) than in controls (57.3 +/- 98.3; P < 0.001). Using the median control value (29.22) as a cutoff, 63% of the cases were distributed above this level (adjusted odds ratio, 1.71; 95% confidence interval, 1.39-2.10). A significant dose-response relationship was observed between adduct quartiles and SCCHN risk (P(trend) < 0.001). Multivariate linear regression analysis revealed that ethnicity and smoking were significant predictors of BPDE-DNA adduct levels in controls. In conclusion, we confirmed the previously reported association between in vitro BPDE-induced DNA adduct levels and SCCHN risk, and the assay may help identify individuals at high risk of developing smoking-related cancers.

Glutathione S-transferase polymorphisms and the synergy of alcohol and tobacco in oral, pharyngeal, and laryngeal carcinoma

Investigations of the ability of polymorphisms in the GSTM1, GSTT1, and GSTP1 genes to alter susceptibility to head and neck squamous cell carcinoma (HNSCC) have examined gene-environment interaction in their detoxification of tobacco-associated carcinogens. Little work has been done to ask if these variant genes also modify the interaction of tobacco and alcohol in the development of HNSCC. To test this hypothesis, we conducted a case-control study, enrolling 692 incident cases of HNSCC and 753 population controls. Information about lifetime tobacco and alcohol use was ascertained through questionnaires, and genotypes for GSTM1, GSTT1, and GSTP1 were determined from constitutional DNA. Genotype frequencies were compared among cases and controls, and the association between genotypes and tobacco use was evaluated on cancer risk through logistic regression. Deletion of GSTM1 was associated with an increased risk for HNSCC [odds ratio (OR), 1.3; 95% confidence interval (95% CI), 1.0-1.6]. GSTT1 deletion was associated with a slight decreased HNSCC risk (OR, 0.8; 95% CI, 0.6-1.0). Among those with GSTM1 present, the OR of cancer for heavy smoking was 2.6 (95% CI, 1.6-4.3) compared with 4.2 for those with the GSTM1 deleted (95% CI, 2.6-6.7). The combination of consuming 10 to 20 alcohol drinks weekly and smoking >45 pack-years was associated with a 13-fold elevated risk (OR, 12.6; 95% CI, 4.0-40.2) among the GSTM1 deleted subjects compared with an OR of 3.6 (95% CI, 1.5-8.7) among the GSTM1 present individuals. These data (showing that the GSTM1 deletion affects on the tobacco and alcohol synergy) suggest that the interaction of these carcinogens is, at least in part, driven by alcohol, enhancing the carcinogenic action of tobacco smoke.

Alleviating the burden of cancer: a perspective on advances, challenges, and future directions

The control of the burden of cancer would be achievable by promoting health-maintaining lifestyle behavioral practices in conjunction with facilitated access to affordable and effective periodic screening and early detection examinations combined with comprehensive treatment services. In a global population exceeding six billion in the year 2002, there were approximately 10.9 million new cancer cases, 6.7 million cancer deaths, and 22.4 million persons surviving from cancer diagnosed in the previous 5 years. In 2020, the world's population is projected to increase to 7.5 billion and will experience 15 million new cancer cases and 12 million cancer deaths. This perspective on advances, challenges, and future directions in cancer epidemiology and prevention reviews the conceptual foundation for multistep carcinogenesis, causal mechanisms associated with chronic inflammation and the microenvironment of the cancer cell, and obesity, energy expenditure, and insulin resistance. Strategic priorities in global cancer control initiatives should embrace these fundamental concepts by targeting tobacco and alcohol consumption, the increasing prevalence of obesity and metabolic sequelae, and persistent microbial infections.

The economics of squamous cell carcinoma of the head and neck

PURPOSE OF REVIEW

The current review presents a brief overview of the recent literature on the costs of squamous cell carcinoma of the head and neck (SCCHN), one of the most common forms of cancer. SCCHN is a relatively deadly disease. Approximately 50% of patients survive to 5 years, and surgery and chemoradiotherapy can leave survivors with pain, disfigurement, and disability that further add to the burden of the disease.

RECENT FINDINGS

Earlier diagnosis of SCCHN increases the likelihood of treating with a single modality, lowers the risk of mortality, decreases medical expenditures, and improves patients' quality of life. Unfortunately, more than one-half of new cases of oral cancer are diagnosed at an advanced stage. Patients with SCCHN have been shown to use significantly more healthcare resources than similar patients without SCCHN, with resource use varying by cancer stage.

SUMMARY

Although there have been a number of treatment innovations for SCCHN in the past 5 years, the lack of economic data complicates the task of evaluating these new interventions. In this time of mounting concerns over healthcare costs, more emphasis on economic data is clearly warranted.

Alcohol and the liver

PURPOSE OF REVIEW

This review aims to acquaint the reader with advances in 2006 in the epidemiology, genetics, detection, pathogenesis and treatment of alcoholic liver disease.

RECENT FINDINGS

Important discoveries have been made in pathogenesis and mechanism of disease, with great emphasis on the many pathways leading to oxidative stress, and the novel mechanism of endoplasmic reticulum stress that is proving to be important in the pathogenesis of many liver diseases. The reliability of ethyl glucuronide and other biomarkers for the detection of alcohol abuse is being better established. There have been no treatment advances for alcoholic liver disease but, on balance, steroids are still favored for carefully selected patients with alcoholic hepatitis. Many compounds tested in rodents may now be available for consideration for clinical trials. Criteria for patient selection and refusal for liver transplantation are being established but the 6 months abstinence rule still holds.

SUMMARY

Insights are being made into the pathogenesis of alcoholic liver disease but safe and effective therapies for both alcoholic hepatitis and alcoholic cirrhosis have yet to be discovered.

Prospective study of interaction between alcohol, NSAID use and polymorphisms in genes involved in the inflammatory response in relation to risk of colorectal cancer

Inflammatory bowl disease predisposes to cancer of the colorectum, and the use of non-steroidal anti-inflammatory drugs (NSAIDs) decreases the risk; hence genetic variations that modify the inflammatory response may alter the risk of colorectal cancer (CRC). The purpose of this study was to determine if polymorphisms associated with an altered inflammatory response are associated with colorectal cancer risk, and to investigate the possible interaction with lifestyle factors such as alcohol use, smoking and NSAID use. We studied 355 adenocarcinoma cases and 753 control persons, nested within the prospective "Diet, Cancer and Health" study. None of the polymorphisms were associated with risk of colorectal cancer. A statistically significant interaction between PPARgamma2 Pro(12)Ala and alcohol was found, where alcohol use was associated with a 22% increased risk of CRC per 10g alcohol/day among carriers of the variant allele but not among homozygous wild type allele carriers (P for interaction=0.02). Moreover, an interaction between DLG5 R30Q and NSAID use was found (P for interaction=0.02). Our results do not suggest that inborn variations in the inflammatory response play any major role in risk of colorectal cancer.

Acetaldehyde induces matrix metalloproteinase-9 gene expression via nuclear factor-kappaB and activator protein 1 signaling pathways in human hepatocellular carcinoma cells: Association with the invasive potential

Alcohol consumption is a significant risk factor for hepatocellular carcinoma (HCC). Alcohol also increases the prevalence of invasion in HCC patients. However, the molecular mechanism on the metastatic effect of alcohol is unclear so far. Herein we demonstrated that acetaldehyde, the primary metabolite of ethanol, increased matrix metalloproteinase-9 (MMP-9) gelatinolytic activity and promoted cell invasion through the up-regulation of MMP-9 gene transcription in HepG2 cells. The transcription of MMP-9 gene was regulated by 10 microM acetaldehyde via inductions of nuclear factor-kappaB (NF-kappaB) and activator protein 1 (AP-1) activities. Acetaldehyde stimulated the translocation of NF-kappaB into nucleus through inhibitory kappaB-alpha (IkappaB-alpha) and c-Jun N-terminal kinase (JNK)/beta-transducin repeat-containing protein (beta-TrCP) signaling pathways. Acetaldehyde also induced AP-1 activity via the phosphorylation of p38 kinase. In conclusion, our findings demonstrated for the first time that acetaldehyde activated NF-kappaB and AP-1 activities via IkappaB, JNK/beta-TrCP, and p38 signaling pathways, resulting in MMP-9 gene expression and hepatocarcinoma cells invasion. These results suggested that acetaldehyde might be a potential factor involved in the invasiveness of HCC in alcoholic patients.

Alcohol consumption and distinct molecular pathways to colorectal cancer

High alcohol consumption is related to colorectal cancer (CRC). Our objective was to study associations between alcohol consumption and risk of CRC according to characteristics of aetiological pathways: the chromosomal instability (CIN) and the microsatellite instability (MIN) pathway. We classified CIN+ tumours (tumours with either a truncating APC mutation, an activating K-ras mutation or overexpression of p53), MIN+ tumours (tumours lacking hMLH1 expression) and CIN- /MIN- tumours (tumours without these defects). In the Netherlands Cohort Study on diet and cancer, 120852 men and women, aged 55-69 years, completed a questionnaire on risk factors for cancer at baseline (1986). Case-cohort analyses were conducted using 573 CRC cases with complete data after 7 x 3 years of follow-up, excluding the first 2 x 3 years. Adjusted incidence rate ratios (RR) and 95 % confidence intervals (CI) were estimated. Compared with abstaining, alcohol consumption of >or=30 g/d was positively associated with the risk of CRC irrespective of genetic or molecular aberrations present, although statistical significance was not reached (RR 1 x 35 (95 % CI 0 x 9-2 x 0) for the CIN+ tumours, RR 1 x 59 (95 % CI 0 x 4-5 x 8) for the MIN+ tumours and RR 1.15 (95 % CI 0 x 5-2 x 7) for the CIN- /MIN- tumours). Beer, wine and liquor consumption were, independent of their alcoholic content, not consistently associated with the risk of CRC within the defined subgroups. In conclusion, our results indicate that a daily alcohol consumption of >or=30 g is associated with an increase in risk of CRC, independent of the presence or absence of the studied characteristics of different aetiological pathways.

Alcohol and head and neck cancer risk in a prospective study

We investigated the relation between head and neck cancer risk and alcohol consumption in the NIH-AARP Diet and Health Study. During 2,203,500 person-years of follow-up, 611 men and 183 women developed head and neck cancer. With moderate drinking (up to one alcoholic drink per day) as the referent group, non-drinkers showed an increased risk of head and neck cancer (men: hazard ratio (HR) 1.68, 95% confidence interval (95% CI) 1.37-2.06; women: 1.46, 1.02-2.08). Among male and female alcohol drinkers, we observed a significant dose-response relationship between alcohol consumption and risk. The HR for consuming >3 drinks per day was significantly higher in women (2.52, 1.46-4.35) than in men (1.48, 1.15-1.90; P for interaction=0.0036). The incidence rates per 100 000 person-years for those who consumed >3 drinks per day were similar in men (77.6) and women (75.3). The higher HRs observed in women resulted from lower incidence rates in the referent group: women (14.7), men (34.4). In summary, drinking >3 alcoholic beverages per day was associated with increased risk in men and women, but consumption of up to one drink per day may be associated with reduced risk relative to non-drinking.

A prospective study of tobacco and alcohol use as risk factors for pharyngeal carcinomas in Singapore Chinese

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a rare disease in most populations; however, in areas of Southeast Asia and North Africa and in the Arctic, undifferentiated NPC is the most frequent pharyngeal malignancy. Although smoking and alcohol have been established firmly as synergistic risk factors for other pharyngeal carcinomas, previous studies on the association between these risk factors and NPC have not been consistent. Therefore, the authors analyzed this relation in a cohort of Singapore Chinese, which is a population with a high incidence of NPC.

METHODS

From 1993 to 1998, a population-based cohort of 61,320 Singapore Chinese ages 45 years to 74 years who were free of cancer completed a comprehensive interview on living conditions and dietary and lifestyle factors. By linkage to Singapore population-based registries, the cohort was followed through 2005, and cancer occurrence was determined. The relative risk of NPC and other oropharyngeal carcinomas in the cohort was investigated by using a Cox proportional hazards model.

RESULTS

In total, 173 NPCs and 75 other oropharyngeal carcinomas were observed during 601,879 person-years of follow-up. Smoking for >40 years was associated with a doubled risk of NPC (relative risk, 2.0; 95% confidence interval, 1.2-3.3), whereas smoking intensity, age at smoking initiation, and alcohol consumption were not associated with NPC risk. In contrast, smoking duration, smoking intensity, age at smoking initiation, and alcohol consumption all were associated with an increased risk of other oropharyngeal carcinoma (P for trend, <.0001).

CONCLUSIONS

Smoking and alcohol influenced the risk of NPC and other oropharyngeal carcinomas differently in a high-incidence NPC population. Long-term smoking was a risk factor for NPC, but alcohol consumption was not.

Induction of DNA strand breaks and oxidative stress in HeLa cells by ethanol is dependent on CYP2E1 expression

Induction of cytochrome P4502E1 (CYP2E1) is considered to be an important mechanism by which ethanol can cause toxicity related to oxidative stress both in vivo and in vitro. In the current study, we used HeLa cells with doxycycline-regulated CYP2E1 expression to test the hypothesis that induction of CYP2E1 could lead to secondary DNA oxidation that could potentially contribute to the carcinogenicity of ethanol in vivo. Overexpression of CYP2E1 protein was not associated with oxidative stress per se as assessed by markers of lipid peroxidation (cis-parinaric acid oxidation), glutathione depletion and elevation of intracellular reactive oxygen species (dichlorofluoroscin oxidation) in the presence or absence of ethanol substrate (10 mM, 24 h). Furthermore, there was no evidence of elevation of frequency of DNA strand breaks as assessed by the comet assay. In contrast, however, after pre-incubation of cells with L-buthionine-(S,R)-sulphoximine (BSO, 10 microM) which caused a 75% reduction in intracellular reduced glutathione (GSH) levels, CYP2E1 expression resulted in oxidative stress as assessed by all of these markers and DNA strand breaks but only in the presence of ethanol (10 mM). No effect was observed under these conditions in control cells not expressing CYP2E1. Furthermore, these effects could be attenuated by co-incubation with 1-aminobenzotriazole (0.5 mM), a suicide inhibitor of P450 activity. In conclusion, in this in vitro model CYP2E1-mediated interaction with ethanol results in the intracellular oxidative stress and the formation of DNA strand breaks which are detectable in cells pre-sensitized by depletion of intracellular levels of GSH.

Preclinical and clinical pharmacology of alcohol dependence

In recent years, advances in neuroscience led to the development of new medications to treat alcohol dependence and especially to prevent alcohol relapse after detoxification. Whereas the earliest medications against alcohol dependence were fortuitously discovered, recently developed drugs are increasingly based on alcohol's neurobiological mechanisms of action. This review discusses the most recent developments in alcohol pharmacotherapy and emphasizes the neurobiological basis of anti-alcohol medications. There are currently three approved drugs for the treatment of alcohol dependence with quite different mechanisms of action. Disulfiram is an inhibitor of the enzyme aldehyde dehydrogenase and acts as an alcohol-deterrent drug. Naltrexone, an opiate antagonist, reduces alcohol craving and relapse in heavy drinking, probably via a modulation of the mesolimbic dopamine activity. Finally, acamprosate helps maintaining alcohol abstinence, probably through a normalization of the chronic alcohol-induced hyperglutamatergic state. In addition to these approved medications, many other drugs have been suggested for preventing alcohol consumption on the basis of preclinical studies. Some of these drugs remain promising, whereas others have produced disappointing results in preliminary clinical studies. These new drugs in the field of alcohol pharmacotherapy are also discussed, together with their mechanisms of action.

Alcohol consumption and risk of bladder cancer in Los Angeles County

The role of alcoholic beverages in bladder carcinogenesis is still unclear, with conflicting evidence from different studies. We investigated the relationship between alcohol consumption and bladder cancer, and the potential interaction between alcohol consumption and other exposures. In a population-based case-control study conducted in Los Angeles County, 1,586 pairs of cases and their matched neighborhood controls were interviewed. Data were analyzed to determine whether bladder cancer risk differs by alcohol consumption, and whether different alcoholic beverages have different effects. The risk of bladder cancer decreased with increasing frequency (p for trend = 0.003) and duration of alcohol consumption (p for trend = 0.017). Subjects who drank more than 4 drinks per day had a 32% lower (odds ratio, 0.68; 95% confidence interval, 0.52-0.90) risk of bladder cancer than those who never drank any alcoholic beverage. Beer (p for trend = 0.002) and wine (p for trend = 0.054) consumption were associated with reduced risk of bladder cancer, while hard liquor was not. The reduction in risk was mostly seen among shorter-term smokers who urinated frequently. Alcohol consumption was strongly associated with a reduced risk of bladder cancer. The effect was modified by the type of alcoholic beverage, cigarette smoking and frequency of urination.

Smokeless tobacco and increased risk of hypopharyngeal and laryngeal cancers: A multicentric case–control study from India

Hypopharyngeal and laryngeal cancers are among the most common cancers in India. In addition to smoking, tobacco chewing may be a major risk factor for some of these cancers in India. Using data from a multicentric case-control study conducted in India that included 513 hypopharyngeal cancer cases, 511 laryngeal cancer cases and 718 controls, we investigated smoking and chewing tobacco products as risk factors for these cancers. Bidi smoking was a stronger risk factor compared to cigarette smoking for cancer of the hypopharynx (OR(bidi) 6.80 vs. OR(cig) 3.82) and supraglottis (OR(bidi) 7.53 vs. OR(cig) 2.14), while the effect of the 2 products was similar for cancer of the glottis (OR(bidi) 5.32 vs. OR(cig) 5.74). Among never-smokers, tobacco chewing was a risk factor for hypopharyngeal cancer, but not for laryngeal cancer. In particular, the risk of hypopharyngeal cancer increased with the use of Khaini (OR 2.02, CI 0.81-5.05), Mawa (OR 3.17, CI 1.06-9.53), Pan (OR 3.34, CI 1.68-6.61), Zarda (OR 3.58, CI 1.20-10.68) and Gutkha (OR 4.59, CI 1.21-17.49). A strong dose-response relationship was observed between chewing frequency and the risk of hypopharyngeal cancer (p(trend) < 0.001). An effect of alcohol on cancer of the hypopharynx and supraglottis was observed only among daily drinkers (OR 2.22, CI 1.11-4.45 and OR 3.76, CI 1.25-11.30, respectively). In summary, this study shows that chewing tobacco products commercially available in India are risk factors for hypopharyngeal cancer, and that the potency of Bidi smoking may be higher than that of cigarette smoking for hypopharyngeal and laryngeal cancers.

Alcohol drinking cessation and its effect on esophageal and head and neck cancers: A pooled analysis

The objective of this study was to conduct a pooled analysis to evaluate the strength of the evidence available in the epidemiological literature on the association between alcohol drinking cessation and reduction in esophageal and head and neck cancer risks. A search using several electronic bibliographic databases was performed for relevant epidemiological literature between 1966 and 2006. A total of 13 unique studies including over 5,000 cases were found. Categorical and third order polynomial (cubic) regression models were fitted to estimate the temporal relationship between years of drinking cessation and risk of cancer. The risk of esophageal cancer significantly increased within the first 2 yr following cessation [odds ratios (ORs)(0-2 yr): 2.50, 95% confidence intervals (CI): 2.23-2.80], then decreased rapidly and significantly after longer periods of abstention (OR(15+ yr): 0.37, 95% CI: 0.33-0.41). An elevated risk, although not strong as for esophageal cancer, was observed for head and neck cancer up to 10 yr of quitting drinking (OR(5-10 yr): 1.26, 95% CI: 1.18-1.35). Such risk only reduced after 10 yr of cessation (OR(10-16 yr): 0.67, 95% CI: 0.63-0.73). After more than 20 yr of alcohol cessation, the risks for both cancers were no longer significantly different from the risk of never drinkers. Our findings demonstrate an important role of alcohol cessation on esophageal and head and neck carcinogenesis.

The burden of cancer attributable to alcohol drinking

We estimated the number of cancer cases and deaths attributable to alcohol drinking in 2002 by sex and WHO subregion, based on relative risks of cancers of the oral cavity, pharynx, esophagus, liver, colon, rectum, larynx and female breast obtained from recent meta- and pooled analyses and data on prevalence of drinkers obtained from the WHO Global Burden of Disease project. A total of 389,100 cases of cancer are attributable to alcohol drinking worldwide, representing 3.6% of all cancers (5.2% in men, 1.7% in women). The corresponding figure for mortality is 232,900 deaths (3.5% of all cancer deaths). This proportion is particularly high among men in Central and Eastern Europe. Among women, breast cancer comprises 60% of alcohol-attributable cancers. Although our estimates are based on simplified assumptions, the burden of alcohol-associated cancer appears to be substantial and needs to be considered when making public health recommendations on alcohol drinking.

Alcohol and the risk of colon and rectal cancer with mutations in the K-ras gene

The first metabolite of alcohol, acetaldehyde, may trigger replication errors and mutations in DNA, which may predispose to developing colorectal cancer (CRC). In a prospective study on colon and rectal cancer, we investigated the following hypotheses: alcohol consumption is associated with an increased risk of mutations in the K-ras oncogene, and beer consumption is associated with an increased risk of G-->A mutations in this gene. Therefore, we studied the associations between consumption of alcohol and alcoholic beverages and the risk of CRC without and with specific K-ras gene mutations. In 1986, 120,852 men and women, aged 55-69 years, completed a questionnaire on risk factors for cancer. The case-cohort approach was used for data processing and analyses. After 7.3 years of follow-up, excluding the first 2.3 years, complete data from 4,076 subcohort members, 428 colon and 150 rectal cancer patients, were available for data analyses. Incidence rate ratios (RRs) and corresponding 95% confidence intervals (95% CIs) were estimated using Cox proportional hazards models. Compared to abstaining, a total alcohol consumption of 30.0 g/day and more was associated with the risk of colon and rectal cancer with and without a K-ras mutation in both men and women. Independent from alcohol intake, liquor consumption when compared to nonliquor consumption was associated with an increased risk of rectal cancer with a wild type K-ras in men (RR: 2.25, 95% CI: 1.0-5.0). Beer consumption was not clearly associated with the risk of colon and rectal tumors harboring G-->A mutations in the K-ras gene in men. This association could not be assessed in women because of sparse beer consumption. In conclusion, alcohol does not seem to be involved in predisposing to CRC through mutations in the K-ras gene, and specifically beer consumption is not associated with colon and rectal tumors harboring a G-->A mutation.

Alcohol intake and colorectal cancer risk: A dose–response meta-analysis of published cohort studies

The epidemiologic evidence support that alcohol intake might be associated with increased colorectal cancer risk. However, the results by anatomic site in the large bowel are inconsistent. We conducted a meta-analysis of prospective cohort studies published between 1990 and June 2005 on the relationship between alcohol intake and colon and rectal cancer. We quantified associations with colon and rectal cancer using meta-analysis of relative risk (RR) associated to the highest versus the lowest category of alcohol intake and meta-analysis of study-specific dose-response slopes using fixed or random effect models depending on the heterogeneity of effects among studies. Sixteen prospective cohort studies including more than 6,300 patients with colorectal cancer were eligible for inclusion. High alcohol intake was significantly associated with increased risk of colon (RR = 1.50; 95% CI = 1.25, 1.79) and rectal cancer (RR = 1.63; 95% CI = 1.35, 1.97) when comparing the highest with the lowest category of alcohol intake, equivalent to a 15% increase of risk of colon or rectal cancer for an increase of 100 g of alcohol intake per week. The relationship did not differ significantly by anatomical site (colon, rectum). Using meta-regression analysis, we identified geographical area where the study was conducted as a possible source of between-study heterogeneity of effects among studies. Lifestyle recommendations for prevention of colorectal cancer should consider limiting alcohol intake.