Alcohol Consumption and Genetic Variation in Methylenetetrahydrofolate Reductase and 5-Methyltetrahydrofolate-Homocysteine Methyltransferase in Relation to Breast Cancer Risk

Department of Social and Preventive Medicine, State University of New York at Buffalo, Buffalo, NY, USA.
Cancer Epidemiology Biomarkers & Prevention (Impact Factor: 4.13). 09/2009; 18(9):2453-9. DOI: 10.1158/1055-9965.EPI-09-0159
Source: PubMed


It has been hypothesized that effects of alcohol consumption on one-carbon metabolism may explain, in part, the association of alcohol consumption with breast cancer risk. The methylenetetrahydrofolate reductase (MTHFR) and 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR) genes express key enzymes in this pathway. We investigated the association of polymorphisms in MTHFR (rs1801133 and rs1801131) and MTR (rs1805087) with breast cancer risk and their interaction with alcohol consumption in a case-control study--the Western New York Exposures and Breast Cancer study. Cases (n = 1,063) were women with primary, incident breast cancer and controls (n = 1,890) were frequency matched to cases on age and race. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated by unconditional logistic regression. We found no association of MTHFR or MTR genotype with risk of breast cancer. In the original case-control study, there was a nonsignificant increased odds of breast cancer among women with higher lifetime drinking. In the current study, there was no evidence of an interaction of genotype and alcohol in premenopausal women. However, among postmenopausal women, there was an increase in breast cancer risk for women who were homozygote TT for MTHFR C677T and had high lifetime alcohol intake (>or=1,161.84 oz; OR, 1.92; 95% CI, 1.13-3.28) and for those who had a high number of drinks per drinking day (>1.91 drinks/day; OR, 1.80; 95% CI, 1.03-3.28) compared with nondrinkers who were homozygote CC. Our findings indicate that among postmenopausal women, increased breast cancer risk with alcohol consumption may be as a result of effects on one-carbon metabolism.

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    • "Thus, women with the TT genotype are at a higher risk of breast cancer than those with other genotypes. In postmenopausal women, the breast cancer risk was increased in women with the C677T MTHFR variant who had high lifetime daily alcohol intake, suggesting that folate metabolism has an impact on cancer development (Platek et al. 2009). As mentioned earlier, chronic alcohol abuse can cause folate deficiency, which is a well-documented risk factor for breast cancer (Sellers et al. 2001). "
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    ABSTRACT: Cancer is one of the most significant diseases associated with chronic alcohol consumption, and chronic drinking is a strong risk factor for cancer, particularly of the upper aerodigestive tract, liver, colorectum, and breast. Several factors contribute to alcohol-induced cancer development (i.e., carcinogenesis), including the actions of acetaldehyde, the first and primary metabolite of ethanol, and oxidative stress. However, increasing evidence suggests that aberrant patterns of DNA methylation, an important epigenetic mechanism of transcriptional control, also could be part of the pathogenetic mechanisms that lead to alcohol-induced cancer development. The effects of alcohol on global and local DNA methylation patterns likely are mediated by its ability to interfere with the availability of the principal biological methyl donor, S-adenosylmethionine (SAMe), as well as pathways related to it. Several mechanisms may mediate the effects of alcohol on DNA methylation, including reduced folate levels and inhibition of key enzymes in one-carbon metabolism that ultimately lead to lower SAMe levels, as well as inhibition of activity and expression of enzymes involved in DNA methylation (i.e., DNA methyltransferases). Finally, variations (i.e., polymorphisms) of several genes involved in one-carbon metabolism also modulate the risk of alcohol-associated carcinogenesis.
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    ABSTRACT: The association between methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms and breast cancer risk has been widely reported, but results were inconsistent and underpowered. To clarify the effects of MTHFR polymorphisms on the risk of breast cancer, an updated meta-analysis of all available studies relating C677T and/or A1298C polymorphisms of MTHFR gene to the risk of breast cancer was conducted. Eligible articles were identified by search of databases including MEDLINE, PubMed, Web of Science, EMBASE and Chinese Biomedical Literature database (CBM) for the period up to January 2010. Finally, a total of 41 studies with 16,480 cases and 22,388 controls were included, all for C677T polymorphism and 20 with 12,170 cases and 15,865 controls for A1298C polymorphism. The pooled ORs were performed for the allele contrasts, additive genetic model, dominant genetic model, and recessive genetic model, respectively. Subgroup analyses were also performed by ethnicity and menopausal status. With respect to C677T polymorphism, significantly elevated breast cancer risk was found in overall analysis (T vs. C: OR = 1.041, 95% CI = 1.009-1.073; TT vs. CC: OR = 1.132, 95% CI = 1.019-1.259; TT vs. CC + CT: OR = 1.119, 95% CI = 1.014-1.236); in the subgroup analysis by ethnicity, significantly increased risk was found in East Asian population (T vs. C: OR = 1.121, 95% CI = 1.016-1.237; TT vs. CC: OR = 1.331, 95% CI = 1.073-1.650; TT vs. CC + CT: OR = 1.265, 95% CI = 1.058-1.513) but not in Caucasian population; in the subgroup analysis by menopausal status, no statistically significant association was found. With respect to A1298C polymorphism, no significant association with breast cancer risk was demonstrated in overall, ethnicity- and menopausal status-based population. It can be concluded that potentially functional MTHFR C677T polymorphism may play a low penetrance role in the development of breast cancer.
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    ABSTRACT: Published data on the association between MTHFR C677T polymorphism and breast cancer risk are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. Medline, PubMed, Embase, and Web of Science were searched. Crude ORs with 95% CIs were used to assess the strength of association between the MTHFR C677T polymorphism and breast cancer risk. The pooled ORs were performed with co-dominant model (CT vs. CC, TT vs. CC), dominant model (CT + TT vs. CC), and recessive model (TT vs. CC + CT), respectively. A total of 37 studies including 15,260 cases and 20,411 controls were involved in this meta-analysis. Overall, significantly elevated breast cancer risk was associated with TT variant genotype in homozygote comparison and dominant genetic model when all studies were pooled into the meta-analysis (TT vs. CC: OR = 1.11, 95% CI = 1.01-1.23; dominant model: OR = 1.04, 95% CI = 1.00-1.09). In the subgroup analysis by ethnicity, significantly increased risks were found for TT allele carriers among Asians (TT vs. CC: OR = 1.18, 95% CI = 1.04-1.35; recessive model: OR = 1.15, 95% CI = 1.03-1.29). When stratified by study design, statistically significantly elevated risk was found in hospital-based studies (TT vs. CC: OR = 1.18, 95% CI = 1.02-1.38; recessive model: OR = 1.17, 95% CI = 1.05-1.29). In the subgroup analysis by menopausal status, statistically significantly increased risk was found among postmenopausal women (CT vs. CC: OR = 1.12, 95% CI = 1.02-1.23; dominant model: OR = 1.11, 95% CI = 1.01-1.22). In conclusion, this meta-analysis suggests that the MTHFR T allele is a low-penetrant risk factor for developing breast cancer.
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