Carcinogenesis Advance Access published online on January 3, 2008
Carcinogenesis, doi:10.1093/carcin/bgm295
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One-carbon metabolism-related gene polymorphisms and risk of breast cancer
1 Division of Epidemiology and Prevention, Aichi Cancer Center Research Institute
2 Department of Planning and Information, Aichi Prefectural Institute of Public Health
3 Department of Breast Oncology, Aichi Cancer Center Hospital
4 Department of Epidemiology, Nagoya University Graduate School of Medicine
Correspondence should be addressed to: Takeshi Suzuki, M.D., Ph.D., Division of Epidemiology and Prevention, Aichi Cancer Center Research Institute, 1-1 Kanokoden, Chikusa-ku Nagoya 464-8681, Japan, Phone: +81-52-762-6111, Fax: +81-52-763-5233, E-mail: t-suzuki{at}aichi-cc.jp
Environmental exposures and/or genetic background in Japanese population, which might contribute to the relatively low breast cancer incidence rates in Japan, have not been clarified in detail. Folate plays an essential role in DNA methylation and synthesis, and thus may be involved in development of breast cancer. Functional polymorphisms in genes encoding one-carbon metabolism enzymes, methylenetetrahydrofolate reductase (MTHFR C677T), methionine synthase (MTR A2756G), methionine synthase reductase (MTRR A66G) and thymidylate synthase (TS), influence folate metabolism, but epidemiologic studies have yielded inconsistent findings. We therefore conducted a case–control study to clarify their associations with breast cancer risk. A total of 456 breast cancer cases and 912 age- and menopausal status- matched non-cancer controls were genotyped for the polymorphisms. Odd ratios (ORs) with 95% confidence intervals (CIs) were estimated using conditional logistic models adjusted for potential confounders and gene-environment interactions between the polymorphisms and folate consumption were also evaluated. We observed an increased risk of postmenopausal breast cancer with the MTHFR 677TT genotype (OR=1.83, 95%CI: 1.08–3.11) with a menopausal status-based analysis. In combination analysis, a significantly elevated OR was found among postmenopausal women with the MTHFR 677TT genotype and lower intake of dietary folate compared with those with 677CC genotype and adequate folate consumption (OR=2.80, 95%CI: 1.11-7.07). In addition, interaction between the MTRR A66G polymorphism and folate intake for risk of postmenopausal breast cancer was observed (interaction P=0.008). Our findings indicated that the MTHFR and MTRR polymorphisms were associated with individual susceptibility to breast cancer among postmenopausal women.
Received November 13, 2007; revised December 15, 2007; accepted December 15, 2007.