title: The MTHFR C677T polymorphism, estrogen exposure and breast cancer risk: a nested case-control study in Taiwan.
abstract: BACKGROUND
  We evaluated the effects of the MTHFR C677T polymorphism and its interaction with estrogen exposure on breast cancer risk in a nested case-control study conducted in Taiwan.
  
  
  METHODS
  A total of 88 histologically confirmed breast cancer cases and 344 cancer-free controls were recruited between July 1992 and December 2000. The MTHFR C677T genotype was determined by a PCR-RFLP-based assay. All subjects completed in-person interviews.
  
  
  RESULTS
  There was a significant trend of breast cancer in relation to prolonged exposure to estrogens prior to the first full-term pregnancy (FFTP) (p for trend = 0.0015). In contrast, there was no statistically significant association between the risk of breast cancer and the MTHFR C677T genotype. However, a significantly elevated risk of breast cancer predisposed by the MTHFR 677T variant genotype (CT and TT) was observed in women with prolonged exposure to estrogens prior to FFTP (adjusted OR = 4.98, 95% CI = 2.00-12.43).
  
  
  CONCLUSIONS
  The results of this study suggest that the MTHFR 677T variant genotype per se may have no overall association with breast cancer risk, but a sizable association could be observed in the presence of relevant environmental exposure.
authors.affiliation: School of Public Health, National Defense Medical Center, Taipei, Taiwan, Republic of China.
authors.forename: Wei-Yu
authors.initials: WY
authors.lastname: Lin
authors.forename: Yu-Ching
authors.initials: YC
authors.lastname: Chou
authors.forename: Mei-Hsuan
authors.initials: MH
authors.lastname: Wu
authors.forename: Han-Bin
authors.initials: HB
authors.lastname: Huang
authors.forename: Yi-Lin
authors.initials: YL
authors.lastname: Jeng
authors.forename: Cho-Chieh
authors.initials: CC
authors.lastname: Wu
authors.forename: Cheng-Pung
authors.initials: CP
authors.lastname: Yu
authors.forename: Jyh-Cherng
authors.initials: JC
authors.lastname: Yu
authors.forename: San-Lin
authors.initials: SL
authors.lastname: You
authors.forename: Tang-Yuan
authors.initials: TY
authors.lastname: Chu
authors.forename: Chien-Jen
authors.initials: CJ
authors.lastname: Chen
authors.forename: Chien-An
authors.initials: CA
authors.lastname: Sun
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000201:enzymology / Q000453:epidemiology / Q000209:etiology* / Q000235:genetics*; D016022:Case-Control Studies; D004967:Estrogens / Q000502:physiology*; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D008572:Menarche; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics*; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012150:Polymorphism, Restriction Fragment Length; D013624:Taiwan / Q000453:epidemiology
chemical_list: D004967:Estrogens; D042965:Methylenetetrahydrofolate Reductase (NADPH2)