title: Endogenous sex steroids in premenopausal women and risk of breast cancer: the ORDET cohort.
abstract: BACKGROUND
  Previous studies showed that higher testosterone levels are associated with greater risk of breast cancer in premenopausal women, but the literature is scant and inconsistent.
  
  
  METHODS
  In a prospective nested case-control study of 104 premenopausal women with incident breast cancer and 225 matched controls, all characterized by regular menstrual cycles throughout their lifetime, we measured the concentration of estradiol, total and free testosterone (FT), progesterone, sex hormone-binding globulin (SHBG), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) in blood samples collected on days 20 through 24 of their cycles.
  
  
  RESULTS
  In logistic regression models, the multivariate odds ratios (ORs) of invasive breast cancer for women in the highest tertile of circulating FT compared with the lowest was 2.43 (95% confidence interval (95% CI), 1.15 to 5.10; Ptrend = 0.03), whereas for total testosterone, the association had the same direction but was not statistically significant (OR, 1.27; 95% CI, 0.62 to 2.61; Ptrend = 0.51). Endogenous progesterone was not statistically associated with breast cancer (OR, 1.16; 95% CI, 0.60 to 2.27; Ptrend = 0.75), nor were the other considered hormones.
  
  
  CONCLUSIONS
  Consistent with previous prospective studies in premenopausal women and our own earlier investigation, we observed that higher levels of FT are positively associated with breast cancer risk in women with regular menstrual cycles throughout their lifetimes. No evidence of risk was found associated with the other endogenous sex steroids.
authors.forename: Eva S
authors.initials: ES
authors.lastname: Schernhammer
authors.forename: Francesca
authors.initials: F
authors.lastname: Sperati
authors.forename: Pedram
authors.initials: P
authors.lastname: Razavi
authors.forename: Claudia
authors.initials: C
authors.lastname: Agnoli
authors.forename: Sabina
authors.initials: S
authors.lastname: Sieri
authors.forename: Franco
authors.initials: F
authors.lastname: Berrino
authors.forename: Vittorio
authors.initials: V
authors.lastname: Krogh
authors.forename: Carlo
authors.initials: C
authors.lastname: Abbagnato
authors.forename: Sara
authors.initials: S
authors.lastname: Grioni
authors.forename: Giovanni
authors.initials: G
authors.lastname: Blandino
authors.forename: Holger J
authors.initials: HJ
authors.lastname: Schunemann
authors.forename: Paola
authors.initials: P
authors.lastname: Muti
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000097:blood* / Q000473:pathology; D016022:Case-Control Studies; D004958:Estradiol / Q000097:blood; D005260:Female; D006801:Humans; D008875:Middle Aged; D017697:Premenopause / Q000097:blood*; D011374:Progesterone / Q000097:blood; D011446:Prospective Studies; D012307:Risk Factors; D013739:Testosterone / Q000097:blood*
chemical_list: D013739:Testosterone; D011374:Progesterone; D004958:Estradiol