title: Free β-human chorionic gonadotropin, total human chorionic gonadotropin and maternal risk of breast cancer.
abstract: BACKGROUND
  We investigated whether the free β-human chorionic gonadotropin (free β-hCG) would provide additional information to that provided by total hCG alone and thus be useful in future epidemiological studies relating hCG to maternal breast cancer risk.
  
  
  METHODS
  Cases (n = 159) and controls (n = 286) were a subset of our previous study within the Northern Sweden Maternity Cohort on total hCG during primiparous pregnancy and breast cancer risk.
  
  
  RESULTS
  The associations between total hCG (hazard ratio: 0.79; 95% CI: 0.49-1.27), free β-hCG (hazard ratio: 0.85; 95% CI: 0.33-2.18) and maternal risk of breast cancer were very similar in all analyses and mutual adjustment for either one had minor effects on the risk estimates.
  
  
  CONCLUSIONS
  In the absence of a reliable assay on intact hCG, total hCG alone can be used in epidemiological studies investigating hCG and breast cancer risk, as free β-hCG does not appear to provide any additional information.
authors.affiliation: Division of Public Health Sciences, Department of Surgery & Siteman Cancer Center, Washington University School of Medicine, St Louis, MO, USA.
authors.forename: Adetunji T
authors.initials: AT
authors.lastname: Toriola
authors.forename: Egle
authors.initials: E
authors.lastname: Tolockiene
authors.forename: Helena
authors.initials: H
authors.lastname: Schock
authors.forename: Helja-Marja
authors.initials: HM
authors.lastname: Surcel
authors.forename: Anne
authors.initials: A
authors.lastname: Zeleniuch-Jacquotte
authors.forename: Goran
authors.initials: G
authors.lastname: Wadell
authors.forename: Paolo
authors.initials: P
authors.lastname: Toniolo
authors.forename: Eva
authors.initials: E
authors.lastname: Lundin
authors.forename: Kjell
authors.initials: K
authors.lastname: Grankvist
authors.forename: Annekatrin
authors.initials: A
authors.lastname: Lukanova
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000097:blood*; D016022:Case-Control Studies; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D005260:Female; D015292:Glycoprotein Hormones, alpha Subunit / Q000097:blood*; D006801:Humans; D008875:Middle Aged; D011247:Pregnancy; D012306:Risk
chemical_list: D018997:Chorionic Gonadotropin, beta Subunit, Human; D015292:Glycoprotein Hormones, alpha Subunit