title: Circulating insulin-like growth factor-I in pregnancy and maternal risk of breast cancer.
abstract: BACKGROUND
  Elevated serum concentrations of insulin-like growth factor (IGF)-I have been associated with increased risk of developing breast cancer. Previously, we reported a similar association in samples obtained during pregnancy. This study was conducted to further characterize the association of IGF-I during pregnancy with maternal breast cancer risk.
  
  
  METHODS
  A case-control study was nested within the Finnish Maternity Cohort. The study was limited to primiparous women younger than 40 years, who donated blood samples during early (median, 12 weeks) pregnancy and delivered a single child at term. Seven hundred nineteen women with invasive breast cancer were eligible. Two controls (n = 1,434) were matched with each case on age and date at blood donation. Serum IGF-I concentration was measured using an Immulite 2000 analyzer. Conditional logistic regression was used to estimate ORs and 95% CIs.
  
  
  RESULTS
  No significant associations were observed between serum IGF-I concentrations and breast cancer risk in both the overall analysis (OR, 1.08; 95% CI, 0.80-1.47) and in analyses stratified by histologic subtype, lag time to cancer diagnosis, age at pregnancy, or age at diagnosis.
  
  
  CONCLUSIONS
  There was no association between IGF-I and maternal breast cancer risk during early pregnancy in this large nested case-control study.
  
  
  CONCLUSIONS
  Serum IGF-I concentrations during early pregnancy may not be related to maternal risk of developing breast cancer.
authors.affiliation: National Institute for Health and Welfare, Oulu, Finland.
authors.forename: Adetunji T
authors.initials: AT
authors.lastname: Toriola
authors.forename: Eva
authors.initials: E
authors.lastname: Lundin
authors.forename: Helena
authors.initials: H
authors.lastname: Schock
authors.forename: Kjell
authors.initials: K
authors.lastname: Grankvist
authors.forename: Eero
authors.initials: E
authors.lastname: Pukkala
authors.forename: Tianhui
authors.initials: T
authors.lastname: Chen
authors.forename: Anne
authors.initials: A
authors.lastname: Zeleniuch-Jacquotte
authors.forename: Paolo
authors.initials: P
authors.lastname: Toniolo
authors.forename: Matti
authors.initials: M
authors.lastname: Lehtinen
authors.forename: Helja-Marja
authors.initials: HM
authors.lastname: Surcel
authors.forename: Annekatrin
authors.initials: A
authors.lastname: Lukanova
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000097:blood* / Q000473:pathology; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D011247:Pregnancy / Q000097:blood*; D017697:Premenopause / Q000097:blood; D012307:Risk Factors
chemical_list: D007334:Insulin-Like Growth Factor I