title: Adolescent dietary phytoestrogen intake and breast cancer risk (Canada).
abstract: OBJECTIVE
  It has been suggested that dietary phytoestrogen intake during adolescence may reduce the risk of developing breast cancer. This population-based case-control study evaluated the association between adolescent dietary phytoestrogen intake and adult breast cancer risk among women in Ontario, Canada.
  
  
  METHODS
  Pathology-confirmed, population-based breast cancer cases, aged 25-74 years, diagnosed between June 2002 and April 2003, were identified using the Ontario Cancer Registry. Population-based controls were recruited, and matched to cases within 5-year age groups. Adolescent phytoestrogen intake was obtained using a brief food frequency questionnaire (n = 3,024 cases, n = 3,420 controls). Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).
  
  
  RESULTS
  Higher phytoestrogen intake (both isoflavones and lignans) during adolescence was associated with a reduced breast cancer risk, and a monotonic trend was observed from the lowest to the highest quartile (OR [Q2] = 0.91, 95% CI 0.79-1.04, OR[Q3] = 0.86, 95% CI 0.75-0.98, and OR[Q4] = 0.71, 95% CI 0.62-0.82, p-trend < 0.001).
  
  
  CONCLUSIONS
  Adolescent dietary phytoestrogen intake may be associated with a decreased risk of adult breast cancer. If verified, this finding has important implications with regard to breast cancer prevention since diet is a potentially modifiable factor.
authors.affiliation: Department of Public Health Sciences, University of Toronto, Toronto, Ont, Canada.
authors.forename: Joanne
authors.initials: J
authors.lastname: Thanos
authors.forename: Michelle
authors.initials: M
authors.lastname: Cotterchio
authors.forename: Beatrice A
authors.initials: BA
authors.lastname: Boucher
authors.forename: Nancy
authors.initials: N
authors.lastname: Kreiger
authors.forename: Lilian U
authors.initials: LU
authors.lastname: Thompson
mesh_terms: D000293:Adolescent; D001943:Breast Neoplasms / Q000178:diet therapy / Q000517:prevention & control; D002170:Canada; D016022:Case-Control Studies; D004032:Diet; D004198:Disease Susceptibility; D005260:Female; D006801:Humans; D016017:Odds Ratio; D048789:Phytoestrogens / Q000008:administration & dosage* / Q000494:pharmacology*; D012042:Registries; D012307:Risk Factors
chemical_list: D048789:Phytoestrogens