title: Serum testosterone and the risk of prostate cancer: potential implications for testosterone therapy.
abstract: OBJECTIVE
  A potential risk of testosterone replacement therapy is an increase in the incidence of prostate cancer, but it is unclear whether higher levels of serum testosterone are associated with a higher risk of prostate cancer. We prospectively evaluated serum androgen concentrations and prostate cancer risk.
  
  
  METHODS
  Included were 794 members of the Baltimore Longitudinal Study of Aging. We estimated the rate ratio (RR) of prostate cancer by entering serial measures of serum total testosterone, dehydroepiandrosterone sulfate, sex hormone binding globulin, calculated free testosterone, and free testosterone index (FTI) into a Cox proportional hazards regression model with simple updating.
  
  
  RESULTS
  Higher calculated free testosterone was associated with an increased age-adjusted risk of prostate cancer {RRs by quartile: 1.00, 1.52 [95% confidence interval (95% CI), 0.93-2.50], 1.16 (95% CI, 0.61-2.20), 2.59 (95% CI, 1.28-5.25); P(trend) = 0.03}, which persisted after excluding measures in men <45 years of age [RRs by quartile: 1.00, 1.33 (95% CI, 0.78-2.25), 1.26 (95% CI, 0.68-2.33), 1.89 (95% CI, 0.99-3.61); P(trend) = 0.03]. Compared to men with eugonadal FTI (> or = 0.153), men with hypogonadal FTI had a decreased risk of prostate cancer (RR, 0.51; 95% CI, 0.31-0.82).
  
  
  CONCLUSIONS
  Higher levels of calculated serum free testosterone are associated with an increased risk of prostate cancer. These findings suggest that men receiving testosterone therapy should be regularly monitored for prostate cancer and underscore the need for prospective trials of testosterone therapy incorporating incidence of prostate cancer as a primary safety end point.
authors.affiliation: The James Buchanan Brady Urological Institute, The Johns Hopkins Hospital, Baltimore, MD 21287, USA. parsonsk@jhmi.edu
authors.forename: J Kellogg
authors.initials: JK
authors.lastname: Parsons
authors.forename: H Ballentine
authors.initials: HB
authors.lastname: Carter
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Platz
authors.forename: E James
authors.initials: EJ
authors.lastname: Wright
authors.forename: Patricia
authors.initials: P
authors.lastname: Landis
authors.forename: E Jeffrey
authors.initials: EJ
authors.lastname: Metter
mesh_terms: D016022:Case-Control Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000209:etiology* / Q000503:physiopathology; D012307:Risk Factors; D013739:Testosterone / Q000097:blood*
chemical_list: D013739:Testosterone