ADH3 genotype, alcohol intake and breast cancer risk

Alcohol Consumption and Cancer Risk: Two Sample Mendelian Randomization

Although numerous observational studies have reported on the association between alcohol consumption and cancer, insufficient studies have estimated the causality. Our study evaluated the causal relationship between various types of cancer according to the frequency of drinking and the amount of alcohol consumed. The research data were obtained from the publicly available MR-Base platform. The frequency and amount of drinking were selected as the exposure, and 16 cancer types were selected as the outcome. Two-sample summary data Mendelian randomization (2SMR) was conducted to examine the causality between alcohol consumption and cancer type. Additionally, for cancers suspected of pleiotropy, outliers were removed and re-analyzed through radial MR. The MR results using the inverse variance weighted (IVW) method were different before and after removing outliers. The biggest differences were found for esophageal cancer and biliary tract cancer. For esophageal cancer, after removing outliers (rs13102973, rs540606, rs650558), the OR (95% CI) was 3.44 (1.19-9.89), which was statistically significant (p = 0.02172). Even in biliary tract cancer, after removing outliers (rs13231886, rs58905411), the OR (95% CI) was 3.86 (0.89-16.859), which was of borderline statistical significance (p = 0.07223). The strongest association was found for esophageal cancer. For other cancers, the evidence was not sufficient to draw conclusions. More research is needed to understand the causality between drinking and cancer.

Epidemiology and Risk Factors for Breast Cancer: 21st Century Advances, Gaps to Address through Interdisciplinary Science

Research methods to study risk factors and prevention of breast cancer have evolved rapidly. We focus on advances from epidemiologic studies reported over the past two decades addressing scientific discoveries, as well as their clinical and public health translation for breast cancer risk reduction. In addition to reviewing methodology advances such as widespread assessment of mammographic density and Mendelian randomization, we summarize the recent evidence with a focus on the timing of exposure and windows of susceptibility. We summarize the implications of the new evidence for application in risk stratification models and clinical translation to focus prevention-maximizing benefits and minimizing harm. We conclude our review identifying research gaps. These include: pathways for the inverse association of vegetable intake and estrogen receptor (ER)-ve tumors, prepubertal and adolescent diet and risk, early life adiposity reducing lifelong risk, and gaps from changes in habits (e.g., vaping, binge drinking), and environmental exposures.

Alcohol and breast cancer

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

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

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

Genetic variation and risk of DNA damage in peripheral blood lymphocytes of Iranian formaldehyde-exposed workers

Formaldehyde (FA) has given positive results for the genetic damage evaluated in human peripheral blood lymphocytes. Polymorphism plays a special role in the toxicity of chemicals. DNA damage in blood cells was evaluated in workers who were occupationally exposed to FA. This study tested the association of alcohol dehydrogenase III (ADH3) and manganese-superoxide dismutase (Mn-SOD) gene polymorphism, with DNA damage of peripheral blood lymphocytes. Gene polymorphisms were evaluated in 54 workers from melamine dinnerware workshops and 34 workers from dairy production workshops. The control and exposed population were matched based on age, smoking, work history and socioeconomic status. DNA damage was evaluated by alkaline comet assay in the peripheral blood lymphocytes. ADH3 and Mn-SOD genotypes were determined in all workers using polymerase chain reaction–restriction fragment length polymorphism method. DNA damage of lymphocyte cells was significantly higher ( p < 0.001) in the exposed individuals in comparison with the control population. The examinations of the exposed group had revealed significantly higher ( p < 0.01) variant of Val/Val of Mn-SOD compared to control group. In workers with ADH32–2 variant, significantly higher levels of DNA damage ( p < 0.01) were observed than the control population with the same genotype. It could be concluded that enzymes involved in the metabolism of FA and oxidative stress controlling are two important effective parameters for DNA damage of peripheral blood lymphocytes in exposed people. These results are regarded as a pioneer investigation for the management of health risks assessment.

Lifetime Alcohol Intake, Binge Drinking Behaviors, and Breast Cancer Risk

The prevalence of binge drinking in the United States is rising. While alcohol is a risk factor for breast cancer, less is known about the impact of episodic heavy drinking. In 2003-2009, women aged 35-74 years who were free of breast cancer were enrolled in the Sister Study (n = 50,884). Residents of the United States or Puerto Rico who had a sister with breast cancer were eligible. Multivariable Cox regression was used to estimate adjusted hazard ratios and 95% confidence intervals for breast cancer. During follow-up (mean = 6.4 years), 1,843 invasive breast cancers were diagnosed. Increased breast cancer risk was observed for higher lifetime alcohol intake (for ≥230 drinks/year vs. <60 drinks/year, hazard ratio (HR) = 1.35, 95% confidence interval (CI): 1.15, 1.58). Relative to low-level drinkers (<60 drinks/year), hazard ratios were increased for ever binge drinking (HR = 1.29, 95% CI: 1.15, 1.45) or blacking out (HR = 1.39, 95% CI: 1.17, 1.64). Compared with low-level drinkers who never binged, moderate drinkers (60-229 drinks/year) who binged had a higher risk (HR = 1.25, 95% CI: 1.08, 1.44). There was evidence of effect modification between moderate lifetime drinking and binging (relative excess risk due to interaction = 0.33, 95% CI: 0.10, 0.57). Our findings support the established association between lifetime alcohol intake and breast cancer and provide evidence for an increased risk associated with heavy episodic drinking, especially among moderate lifetime drinkers.

Neurotoxicity effect of formaldehyde on occupational exposure and influence of individual susceptibility to some metabolism parameters

Over the years, neurotoxicity and cognitive dysfunction have separately been associated with endogenous formaldehyde and reduction of acetylcholine signals. However, a limited number of studies have shown a relationship between cholinergic neurotransmitter and formaldehyde exposure. Therefore, the aim of this study was to assess the neurological effect on workers from melamine-dish preparation workshop, who were exposed to formaldehyde. A total of 35 formaldehyde-exposed workers were compared with 32 control employees from the food industry. Occupational exposure to formaldehyde was conducted using the National Institute of Occupational Safety and Health 3500 methods. Using the Ellman method, acetylcholinesterase (AChE) as a biomarker for neurotoxicity was analyzed in blood erythrocyte. The effects of alcohol dehydrogenase III (ADH3) and Mn-superoxide dismutase (Mn-SOD) polymorphism were used to survey the level of AChE activity. In this study, it was found that exposure to airborne formaldehyde increased from 0.024 to 0.74 ppm and the median personnel exposure was 0.057. Induction of AChE activity was observed in formaldehyde-exposed workers as compared with the control group (p < 0.01), while AChE activity increased in 64 % of the exposed subjects. Spearman's correlation (p < 0.02) was used to evaluate the association between AChE activity and occupational exposure to formaldehyde. Exposed subjects containing ADH3_2-2 genotype had higher AChE than others. The findings of this study suggest that the neurotoxic effect of formaldehyde depends on the AChE activity, which is affected by metabolism. It can be concluded that cholinergic signal reduction in cases of cognitive dysfunction could be associated with endogenous formaldehyde.

Alcohol Use and Breast Cancer: A Critical Review

The objective of this study was to outline the biological pathways of alcohol-attributable breast cancer, the epidemiological risk relationship between alcohol consumption and breast cancer, and the global burden of breast cancer incidence and mortality attributable to alcohol consumption, with a focus on light drinking. First, the literature regarding the biological mechanisms of how alcohol affects the risk of breast cancer was reviewed and summarized. Second, a search of meta-analyses that evaluated the risk relationship between alcohol consumption and breast cancer was conducted. Last, the burden of alcohol-attributable breast cancer incidence and mortality was estimated by means of a Population-Attributable Fraction methodology. Data on alcohol consumption were obtained from the Global Information System on Alcohol and Health, and data on cancer incidence and mortality were obtained from the GLOBOCAN database. Alcohol consumption affects breast cancer risk through the alteration in hormone levels and the associated biological pathways, the metabolism of ethanol resulting in carcinogens, and the inhibition of the one carbon metabolism pathway. The systematic review found 15 meta-analyses on the risk relationship between alcohol consumption (also light consumption) and the risk of breast cancer. All but 2 of these analyses showed a dose-response relationship between alcohol consumption and the risk of breast cancer. An estimated 144,000 (95% confidence interval [CI]: 88,000 to 200,000) breast cancer cases and 38,000 (95% CI: 2,400 to 53,000) breast cancer deaths globally in 2012 were attributable to alcohol, with 18.8% of these cases and 17.5% of these deaths affecting women who were light alcohol consumers. All levels of evidence showed a risk relationship between alcohol consumption and the risk of breast cancer, even at low levels of consumption. Due to this strong relationship, and to the amount of alcohol consumed globally, the incidence of and mortality from alcohol-attributable breast cancer is large.

Effects of the lifestyle habits in breast cancer transcriptional regulation

Through research carried out in the last 25 years about the breast cancer etiology, it has been possible to estimate that less than 10 % of patients who are diagnosed with the condition are carriers of some germline or somatic mutation. The clinical reports of breast cancer patients with healthy twins and the development of disease in women without high penetrance mutations detected, warn the participation more factors in the transformation process. The high incidence of mammary adenocarcinoma in the modern woman and the urgent need for new methods of prevention and early detection have demanded more information about the role that environment and lifestyle have on the transformation of mammary gland epithelial cells. Obesity, alcoholism and smoking are factors that have shown a close correlation with the risk of developing breast cancer. And although these conditions affect different cell regulation levels, the study of its effects in the mechanisms of transcriptional and epigenetic regulation is considered critical for a better understanding of the loss of identity of epithelial cells during carcinogenesis of this tissue. The main objective of this review was to establish the importance of changes occurring to transcriptional level in the mammary gland as a consequence of acute or chronic exposure to harmful products such as obesity-causing foods, ethanol and cigarette smoke components. At analyze the main studies related to topic, it has concluded that the understanding of effects caused by the lifestyle factors in performance of the transcriptional mechanisms that determine gene expression of the mammary gland epithelial cells, may help explain the development of this disease in women without genetic propensity and different phenotypic manifestations of this cancer type.

Links between alcohol consumption and breast cancer: a look at the evidence

Alcohol consumption by adult women is consistently associated with risk of breast cancer. Several questions regarding alcohol and breast cancer need to be addressed. Menarche to first pregnancy represents a window of time when breast tissue is particularly susceptible to carcinogens. Youth alcohol consumption is common in the USA, largely in the form of binge drinking and heavy drinking. Whether alcohol intake acts early in the process of breast tumorigenesis is unclear. This review aims to focus on the influences of timing and patterns of alcohol consumption and the effect of alcohol on intermediate risk markers. We also review possible mechanisms underlying the alcohol-breast cancer association.

Alcohol and breast cancer: reconciling epidemiological and molecular data

Breast cancer is the most diagnosed cancer in women worldwide. Epidemiological studies have suggested a possible causative role of alcohol consumption as a risk factor for breast cancer. However, such conclusions should be interpreted with considerable caution for several reasons. While epidemiological studies can help identify the roots of health problems and disease incidence in a community, they are by necessity associative and cannot determine cause and effect relationships. In addition, all these studies rely on self-reporting to determine the amount and type of alcoholic beverage consumed, which introduces recall bias. This is documented in a recent study which stated that the apparent increased risk of cancer among light-moderate drinkers may be "substantially due to underreporting of intake." Another meta-analysis about alcohol and breast cancer declared "the modest size of the association and variation in results across studies leave the causal role of alcohol in question." Furthermore, breast cancer develops over decades; thus, correlations between alcohol consumption and breast cancer cannot be determined in epidemiological studies with windows of alcohol exposure that captures current or recent alcohol intake, after clinical diagnosis. Numerous risk factors are involved in breast carcinogenesis; some are genetic and beyond the control of a woman; others are influenced by lifestyle factors. Breast cancer is a heterogeneous and polygenic disease which is further influenced by epigenetic mechanisms that affect the transciptomes, proteomes and metabolomes, and ultimately breast cancer evolution. Environmental factors add another layer of complexity by their interactions with the susceptibility genes for breast cancer and metabolic diseases. The current state-of-knowledge about alcohol and breast cancer association is ambiguous and confusing to both a woman and her physician. Confronting the huge global breast cancer issue should be addressed by sound science. It is advised that women with or without a high risk for breast cancer should avoid overconsumption of alcohol and should consult with their physician about risk factors involved in breast cancer. Since studies associating moderate alcohol consumption and breast cancer are contradictory, a woman and her physician should weigh the risks and benefits of moderate alcohol consumption.

Female breast cancer and alcohol consumption: a review of the literature

CONTEXT

Consumption of alcoholic beverages is one of the single most important known and modifiable risk factor for human cancer. Among women, breast cancer is the most common cancer worldwide and the leading cause of cancer-related mortality. Consumption of alcoholic beverages is causally associated with female breast cancer and the association shows a linear dose-response relationship. The role of heavy drinking has been long recognized and even a moderate intake is associated with an increased risk for breast cancer. The present review is an update of the current evidence on the association between alcohol consumption and breast cancer risk. The aim is to gain further insight into this association and to improve our current understanding of the effects of the major modifying factors.

EVIDENCE ACQUISITION

Epidemiologic and experimental studies published since the most recent International Agency for Research on Cancer (IARC) Monograph on alcoholic beverages were identified in PubMed using a combination of keywords such as alcohol, breast cancer, polymorphisms, menopausal status.

EVIDENCE SYNTHESIS

Cumulative lifetime consumption, drinking frequency, drinking patterns and timing of exposure each modulate the association between alcohol consumption and breast cancer. Hormonal status, genetic polymorphisms, and nutritional factors may interact with ethanol metabolism and further influence breast cancer risk.

CONCLUSIONS

Better standardization among experimental and epidemiologic designs in assessing alcohol intake and timing of exposure may improve our understanding of the heterogeneity observed across studies, possibly allowing the quantification of the effects of occasional heavy drinking and the identification of a window of higher susceptibility to breast cancer development.

Wine, Food and Health

Wine has historically been associated with religious rights, used as a salubrious beverage, employed as a medication as well as a medicinal solvent, and consumed as a food accompaniment. It is the latter that is most intimately associated in the minds of most modern consumers. Despite this, there is little flavor commonality on which pairing could be based. The first section of the chapter examines this feature, and wine’s primary role as a palate cleanser and food condiment. The synergistic role of food and wine in suppressing each other’s least pleasant attributes is also explained. The final section deals with the latest evidence relating to the many beneficial health effects of moderate wine consumption, shortfalls in the data, headache induction, dental erosion, and conditions under which wine intake is contraindicated.

Association between polymorphisms in glutathione peroxidase and selenoprotein P genes, glutathione peroxidase activity, HRT use and breast cancer risk

Breast cancer (BC) is one of the most common cancers in women. Evidence suggests that genetic variation in antioxidant enzymes could influence BC risk, but to date the relationship between selenoproteins and BC risk remains unclear. In this report, a study population including 975 Danish cases and 975 controls matched for age and hormone replacement therapy (HRT) use was genotyped for five functional single nucleotide polymorphisms (SNPs) in SEPP1, GPX1, GPX4 and the antioxidant enzyme SOD2 genes. The influence of genetic polymorphisms on breast cancer risk was assessed using conditional logistic regression. Additionally pre-diagnosis erythrocyte GPx (eGPx) activity was measured in a sub-group of the population. A 60% reduction in risk of developing overall BC and ductal BC was observed in women who were homozygous Thr carriers for SEPP1 rs3877899. Additionally, Leu carriers for GPX1 Pro198Leu polymorphism (rs1050450) were at ∼2 fold increased risk of developing a non-ductal BC. Pre-diagnosis eGPx activity was found to depend on genotype for rs713041 (GPX4), rs3877899 (SEPP1), and rs1050450 (GPX1) and on HRT use. Moreover, depending on genotype and HRT use, eGPx activity was significantly lower in women who developed BC later in life compared with controls. Furthermore, GPx1 protein levels increased in human breast adenocarcinoma MCF7 cells exposed to β-estradiol and sodium selenite.In conclusion, our data provide evidence that SNPs in SEPP1 and GPX1 modulate risk of BC and that eGPx activity is modified by SNPs in SEPP1, GPX4 and GPX1 and by estrogens. Our data thus suggest a role of selenoproteins in BC development.

Alcohol Intake and Breast Cancer Risk: Weighing the Overall Evidence

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

Lysine-specific demethylase 1 in breast cancer cells contributes to the production of endogenous formaldehyde in the metastatic bone cancer pain model of rats

Background

Bone cancer pain seriously affects the quality of life of cancer patients. Our previous study found that endogenous formaldehyde was produced by cancer cells metastasized into bone marrows and played an important role in bone cancer pain. However, the mechanism of production of this endogenous formaldehyde by metastatic cancer cells was unknown in bone cancer pain rats. Lysine-specific demethylase 1 (LSD1) is one of the major enzymes catalyzing the production of formaldehyde. The expression of LSD1 and the concentration of formaldehyde were up-regulated in many high-risk tumors.

Objective

This study aimed to investigate whether LSD1 in metastasized MRMT-1 breast cancer cells in bone marrows participated in the production of endogenous formaldehyde in bone cancer pain rats.

Methodology/Principal Findings

Concentration of the endogenous formaldehyde was measured by high performance liquid chromatography (HPLC). Endogenous formaldehyde dramatically increased in cultured MRMT-1 breast cancer cells in vitro, in bone marrows and sera of bone cancer pain rats, in tumor tissues and sera of MRMT-1 subcutaneous vaccination model rats in vivo. Formaldehyde at a concentration as low as the above measured (3 mM) induced pain behaviors in normal rats. The expression of LSD1 which mainly located in nuclei of cancer cells significantly increased in bone marrows of bone cancer pain rats from 14 d to 21 d after inoculation. Furthermore, inhibition of LSD1 decreased the production of formaldehyde in MRMT-1 cells in vitro. Intraperitoneal injection of LSD1 inhibitor pargyline from 3 d to 14 d after inoculation of MRMT-1 cancer cells reduced bone cancer pain behaviors.

Conclusion

Our data in the present study, combing our previous report, suggested that in the endogenous formaldehyde-induced pain in bone cancer pain rats, LSD1 in metastasized cancer cells contributed to the production of the endogenous formaldehyde.

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

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

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

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Epidemiology and pathophysiology of alcohol and breast cancer: Update 2012

AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The use of complete-case and multiple imputation-based analyses in molecular epidemiology studies that assess interaction effects

BACKGROUND

In molecular epidemiology studies biospecimen data are collected, often with the purpose of evaluating the synergistic role between a biomarker and another feature on an outcome. Typically, biomarker data are collected on only a proportion of subjects eligible for study, leading to a missing data problem. Missing data methods, however, are not customarily incorporated into analyses. Instead, complete-case (CC) analyses are performed, which can result in biased and inefficient estimates.

METHODS

Through simulations, we characterized the performance of CC methods when interaction effects are estimated. We also investigated whether standard multiple imputation (MI) could improve estimation over CC methods when the data are not missing at random (NMAR) and auxiliary information may or may not exist.

RESULTS

CC analyses were shown to result in considerable bias and efficiency loss. While MI reduced bias and increased efficiency over CC methods under specific conditions, it too resulted in biased estimates depending on the strength of the auxiliary data available and the nature of the missingness. In particular, CC performed better than MI when extreme values of the covariate were more likely to be missing, while MI outperformed CC when missingness of the covariate related to both the covariate and outcome. MI always improved performance when strong auxiliary data were available. In a real study, MI estimates of interaction effects were attenuated relative to those from a CC approach.

CONCLUSIONS

Our findings suggest the importance of incorporating missing data methods into the analysis. If the data are MAR, standard MI is a reasonable method. Auxiliary variables may make this assumption more reasonable even if the data are NMAR. Under NMAR we emphasize caution when using standard MI and recommend it over CC only when strong auxiliary data are available. MI, with the missing data mechanism specified, is an alternative when the data are NMAR. In all cases, it is recommended to take advantage of MI's ability to account for the uncertainty of these assumptions.

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

Within the Netherlands Cohort Study (1986), we examined associations between alcohol consumption, the alcohol dehydrogenase 1C (ADH1C) genotype, and risk of colorectal cancer (CRC). After a follow-up period of 7.3 years, 594 CRC cases with information on genotype and baseline alcohol intake were available for analyses. Adjusted incidence rate ratios (RRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models. In subjects who reported to have consumed equal amounts of total alcohol both 5 years before baseline and at baseline, drinkers of ≥30g of alcohol per day with the ADH1C*2/*2 genotype were associated-although not statistically significant-with an increased risk of CRC relative to abstainers with the ADH1C*1/*1 genotype (RR: 1.91, 95% CI: 0.68, 5.34). The risk estimate in this exposure group increased slightly when compared with light drinkers of ≥0.5-<5g/day with the ADH1C*1/*1 genotype (RR: 2.32, 95% CI: 0.80, 6.72). The interaction term however, was not statistically significant (P>.05). In subjects who reported to have consumed equal amounts of total alcohol both 5 years before baseline and at baseline, drinkers of ≥30g of alcohol per day were associated-although not statistically significant-with an increased risk of CRC relative to abstainers (RR: 1.38, 95% CI: 0.80, 2.38). This risk estimate for high-level drinkers became stronger when compared with light drinkers (RR: 1.74, 95% CI: 1.01, 2.99). As main effect of genotype, we observed that the ADH1C*2/*2 genotype was associated with a 42% increase in risk of CRC when compared with the ADH1C*1/*1 genotype. In conclusion, both genotype and alcohol consumption were associated with an increased risk of CRC. Owing to limited statistical power, we found no apparent evidence for the ADH1C genotype as effect modifier of the relationship between alcohol intake and CRC. Nevertheless, the interaction deserves further investigation in larger genetic epidemiologic studies.

Tumor tissue-derived formaldehyde and acidic microenvironment synergistically induce bone cancer pain

BACKGROUND

There is current interest in understanding the molecular mechanisms of tumor-induced bone pain. Accumulated evidence shows that endogenous formaldehyde concentrations are elevated in the blood or urine of patients with breast, prostate or bladder cancer. These cancers are frequently associated with cancer pain especially after bone metastasis. It is well known that transient receptor potential vanilloid receptor 1 (TRPV1) participates in cancer pain. The present study aims to demonstrate that the tumor tissue-derived endogenous formaldehyde induces bone cancer pain via TRPV1 activation under tumor acidic environment.

METHODOLOGY/PRINCIPAL FINDINGS

Endogenous formaldehyde concentration increased significantly in the cultured breast cancer cell lines in vitro, in the bone marrow of breast MRMT-1 bone cancer pain model in rats and in tissues from breast cancer and lung cancer patients in vivo. Low concentrations (1 approximately 5 mM) of formaldehyde induced pain responses in rat via TRPV1 and this pain response could be significantly enhanced by pH 6.0 (mimicking the acidic tumor microenvironment). Formaldehyde at low concentrations (1 mM to 100 mM) induced a concentration-dependent increase of [Ca(2+)]i in the freshly isolated rat dorsal root ganglion neurons and TRPV1-transfected CHO cells. Furthermore, electrophysiological experiments showed that low concentration formaldehyde-elicited TRPV1 currents could be significantly potentiated by low pH (6.0). TRPV1 antagonists and formaldehyde scavengers attenuated bone cancer pain responses.

CONCLUSIONS/SIGNIFICANCE

Our data suggest that cancer tissues directly secrete endogenous formaldehyde, and this formaldehyde at low concentration induces metastatic bone cancer pain through TRPV1 activation especially under tumor acidic environment.

Acetaldehyde as an underestimated risk factor for cancer development: role of genetics in ethanol metabolism

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

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Carcinogenicity of acetaldehyde in alcoholic beverages: risk assessment outside ethanol metabolism

AIMS

In addition to being produced in ethanol metabolism, acetaldehyde occurs naturally in alcoholic beverages. Limited epidemiological evidence points to acetaldehyde as an independent risk factor for cancer during alcohol consumption, in addition to the effects of ethanol. This study aims to estimate human exposure to acetaldehyde from alcoholic beverages and provide a quantitative risk assessment.

METHODS

The human dietary intake of acetaldehyde via alcoholic beverages was estimated based on World Health Organization (WHO) consumption data and literature on the acetaldehyde contents of different beverage groups (beer, wine, spirits and unrecorded alcohol). The risk assessment was conducted using the European Food Safety Authority's margin of exposure (MOE) approach with benchmark doses obtained from dose-response modelling of animal experiments. Life-time cancer risk was calculated using the T25 dose descriptor.

RESULTS

The average exposure to acetaldehyde from alcoholic beverages was estimated at 0.112 mg/kg body weight/day. The MOE was calculated to be 498, and the life-time cancer risk at 7.6 in 10,000. Higher risk may exist for people exposed to high acetaldehyde contaminations, as we have found in certain unrecorded alcohol beverages in Guatemala and Russia, for which we have demonstrated possible exposure scenarios, with risks in the range of 1 in 1000.

CONCLUSIONS

The life-time cancer risks for acetaldehyde from alcoholic beverages greatly exceed the usual limits for cancer risks from the environment set between 1 : 10,000 and 1 : 1,000,000. Alcohol consumption has thus been identified as a direct source of acetaldehyde exposure, which in conjunction with other sources (food flavourings, tobacco) results in a magnitude of risk requiring intervention. An initial public health measure could be to reduce the acetaldehyde content in alcoholic beverages as low as technologically possible, and to restrict its use as a food flavour additive.

Alcohol and genetic polymorphisms: effect on risk of alcohol-related cancer

Public health guidelines aim to limit the consumption of alcoholic beverages worldwide and the subsequent health burden. In particular, alcohol consumption is an avoidable risk factor for cancer. In human beings, ethanol in alcoholic drinks is mainly oxidised in the liver by alcohol dehydrogenases to acetaldehyde, and is further detoxified to acetate by aldehyde dehydrogenases. Functional variants in genes involved in alcohol metabolism result in differences between individuals in exposure to carcinogenic acetaldehyde, suggesting a possible interaction of genetic susceptibility and alcohol exposure in cancer. We reviewed available studies of the combined effects of alcohol drinking and genetic polymorphisms on alcohol-related cancer risk. Most available data were for polymorphisms in alcohol and folate metabolism. We give an overview of published studies on the combined effects of alcohol drinking and polymorphisms in genes for alcohol dehydrogenase (ADH), aldehyde dehydrogenase (ALDH), cytochrome P450 2E1, and methylene-tetrahydrofolate reductase on the risk of alcohol-related cancer. Current data lend support to a role of polymorphisms ADH1B and ALDH2 combined with alcohol consumption in cancer. Other available data are insufficient or inconclusive, highlighting the need for additional studies.

Alcohol intake over the life course and mammographic density

Alcohol intake is one of the few modifiable risk factors for breast cancer. Current alcohol intake has been associated with mammographic density, a strong intermediate marker of breast cancer risk, though few studies have examined the effect of both current and average lifetime alcohol intake. We interviewed 262 participants from a New York birth cohort (born 1959-1963) and obtained mammograms from 163 (71.5% of participants with a mammogram). We collected information on alcohol intake by beverage type separately for each decade of life. We used multivariable linear models to assess the associations between current and average lifetime alcohol intake and mammographic density using a quantitative measure of density from digitized images. Overall, current alcohol intake was more strongly associated with mammographic density than average lifetime alcohol intake; compared with nondrinkers, those with current intake of seven or more servings per week had on average 12.3% (95% CI: 4.3, 20.4) higher density, adjusted for average lifetime alcohol intake, age, and body mass index. We observed a consistent inverse association for red wine intake and mammographic density, suggesting that the positive association between mammographic density and overall alcohol intake was driven by other types of alcoholic beverages. Our findings support an association between current alcohol intake and increased mammographic density independent of the effect of average lifetime alcohol intake. If replicated, our study suggests that reducing current alcohol consumption, particularly beer and white wine intake, may be a means of reducing mammographic density regardless of intake earlier in life.

Contribution of alcohol and tobacco use in gastrointestinal cancer development

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

Estrogen-biosynthesis gene CYP17 and its interactions with reproductive, hormonal and lifestyle factors in breast cancer risk: results from the Long Island Breast Cancer Study Project

The genes that are involved in estrogen biosynthesis, cellular binding and metabolism may contribute to breast cancer susceptibility. We examined the effect of the CYP17 promoter T --> C polymorphism and its interactions with the reproductive history, exogenous hormone use and selected lifestyle risk factors on breast cancer risk among 1037 population-based incident cases and 1096 population-based controls in the Long Island Breast Cancer Study Project. Overall, there were no associations between the CYP17 genotype and breast cancer risk. Among postmenopausal women, the joint exposure to higher body mass index (BMI) and the variant C allele was associated with an increased risk of breast cancer [odds ratio (OR), 1.60; 95% confidence interval (CI), 1.15-2.22]. The joint exposure to the variant C allele and long-term use of hormone replacement therapy (HRT) (>51 months) was related to an increased risk of breast cancer (OR, 1.51; 95% CI, 0.99-2.31) especially estrogen receptor-positive, progesterone receptor-positive breast cancer (OR, 1.87; 95% CI, 1.08-3.25). Among the control population, the CYP17 variant C allele was inversely associated with long-term use of postmenopausal HRT and a higher BMI in postmenopausal women. In conclusion, the findings suggest that the CYP17 variant C allele may increase breast cancer risk in conjunction with long-term HRT use and high BMI in postmenopausal women.

Proteome analysis of human gastric cardia adenocarcinoma by laser capture microdissection

Background

The incidence of gastric cardiac adenocarcinoma (GCA) has been increasing in the past two decades in China, but the molecular changes relating to carcinogenesis have not been well characterised.

Methods

In this study, we used a comparative proteomic approach to analyse the malignant and nonmalignant gastric cardia epithelial cells isolated by navigated laser capture microdissection (LCM) from paired surgical specimens of human GCA.

Results

Twenty-seven spots corresponding to 23 proteins were consistently differentially regulated. Fifteen proteins were shown to be up-regulated, while eight proteins were shown to be down-regulated in malignant cells compared with nonmalignant columnar epithelial cells. The identified proteins appeared to be involved in metabolism, chaperone, antioxidation, signal transduction, apoptosis, cell proliferation, and differentiation. In addition, expressions of HSP27, 60, and Prx-2 in GCA specimens were further confirmed by immunohistochemical and western blot analyses.

Conclusion

These data indicate that the combination of navigated LCM with 2-DE provides an effective strategy for discovering proteins that are differentially expressed in GCA. Such proteins may contribute in elucidating the molecular mechanisms of GCA carcinogenesis. Furthermore, the combination provides potential clinical biomarkers that aid in early detection and provide potential therapeutic targets.

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

OGG1 polymorphisms and breast cancer risk

The role of oxidative stress in breast cancer risk is still unclear. OGG1 encodes an 8-oxoguanine DNA glycosylase/AP lyase that catalyzes the removal of 8-oxodeoxyguanosine from DNA. 8-Oxodeoxyguanosine, the most abundant lesion generated by oxidative stress, is highly mutagenic. Environmental sources of oxidative stress, such as alcohol consumption, cigarette smoking, high body mass index (BMI), and low fruits and vegetables intake, may modify the association of genetic polymorphisms with breast cancer risk. We investigated the association between three genetic polymorphisms in OGG1 (Ser(326)Cys, 7143A/G, and 11657A/G) and breast cancer risk among 1,058 cases and 1,102 controls participating in the Long Island Breast Cancer Study Project. No associations were observed between individual OGG1 polymorphisms, haplotypes, or diplotypes and breast cancer. The association between having at least one variant allele and breast cancer risk was stronger among moderate alcohol drinkers for Ser(326)Cys [odds ratio (OR), 1.82; 95% confidence interval (95% CI), 1.06-3.10] relative to nondrinkers with the wild-type genotype and among those with higher BMI for 7143A/G (OR, 1.47; 95% CI, 1.10-1.96) and for 11657A/G (OR, 1.41; 95% CI, 1.05-1.88), relative to women with BMI < 25 kg/m(2) and the wild-type genotype. However, the patterns were not seen for all three single nucleotide polymorphisms (SNP) nor were there any clear allele dose associations; only one interaction was statistically significant, assuming a multiplicative model (11657A/G, P(interaction) = 0.04). In summary, although we found some differences between the three OGG1 SNPs and breast cancer risk among moderate alcohol drinkers and women with higher BMI, replication of these results is needed to rule out spurious findings. In addition, data on functionality of these polymorphisms are crucial to understand if these modest differences are important.