title: Polymorphic catechol-O-methyltransferase gene, duration of estrogen exposure, and breast cancer risk: a nested case-control study in Taiwan.
abstract: BACKGROUND
  Polymorphic catechol-O-methyltransferase (COMT) catalyzes the O-methylation of catechol estrogens, which are hypothesized to participate in estrogen-induced carcinogenesis.
  
  
  METHODS
  We examined 87 cases and 341 population controls in Taiwan to determine the association between the functional genetic Val158Met polymorphism in membrane-bound form of COMT gene and female breast cancer risk. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by conditional logistic regression.
  
  
  RESULTS
  There was no overall association between COMT genotype and individual susceptibility to breast cancer. However, COMT-L variant genotypes appear to pose increased risk of breast cancer in women with greater duration from menarche to first full-term pregnancy (>8 years) (OR, 2.67; 95% CI, 1.00-7.36).
  
  
  CONCLUSIONS
  This study based on limited sample sizes suggests that there may be no overall association of COMT genotype with breast cancer, but the COMT-L allele could pose enhanced risk of breast cancer in the presence of relevant environmental exposures, as most low penetrance gene are expected to act through gene-environment interactions.
authors.affiliation: School of Public Health, National Defense Medical Center, Taipei 114, 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: Yi-Lin
authors.initials: YL
authors.lastname: Jeng
authors.forename: Han-Bin
authors.initials: HB
authors.lastname: Huang
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 / Q000209:etiology* / Q000235:genetics*; D016022:Case-Control Studies; D002394:Catechol O-Methyltransferase / Q000235:genetics / Q000378:metabolism; D004781:Environmental Exposure; D004967:Estrogens / Q000009:adverse effects*; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D008875:Middle Aged; D016017:Odds Ratio; D011110:Polymorphism, Genetic; D013624:Taiwan
chemical_list: D004967:Estrogens; D002394:Catechol O-Methyltransferase