title: Low free testosterone levels predict disease reclassification in men with prostate cancer undergoing active surveillance.
abstract: OBJECTIVE
  To determine whether total testosterone and free testosterone levels predict disease reclassification in a cohort of men with prostate cancer (PCa) on active surveillance (AS).
  
  
  METHODS
  Total testosterone and free testosterone concentrations were determined at the time the men began the AS protocol. Statistical analysis was performed using Student's t-test and a chi-squared test to compare groups. Odds ratios (ORs) with 95% confidence intervals (CIs) were obtained using univariate logistic regression. Receiver-operator characteristic curves were generated to determine the investigated testosterone thresholds. Kaplan-Meier curves were used to estimate time to disease reclassification. A Cox proportional hazard regression model was used for multivariate analysis.
  
  
  RESULTS
  A total of 154 men were included in the AS cohort, of whom 54 (35%) progressed to active treatment. Men who had disease reclassification had significantly lower free testosterone levels than those who were not reclassified (0.75 vs 1.02 ng/dL, P = 0.03). Men with free testosterone levels <0.45 ng/dL had a higher rate of disease reclassification than patients with free testosterone levels ≥0.45 (P = 0.032). Free testosterone levels <0.45 ng/dL were associated with a several-fold increase in the risk of disease reclassification (OR 4.3, 95% CI 1.25-14.73). Multivariate analysis showed that free testosterone and family history of PCa were independent predictors of disease reclassification.
  
  
  CONCLUSIONS
  Free testosterone levels were lower in men with PCa who had reclassification during AS. Men with moderately severe reductions in free testosterone level are at increased risk of disease reclassification.
authors.affiliation: Departamento de Urología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Ignacio F
authors.initials: IF
authors.lastname: San Francisco
authors.forename: Pablo A
authors.initials: PA
authors.lastname: Rojas
authors.forename: William C
authors.initials: WC
authors.lastname: DeWolf
authors.forename: Abraham
authors.initials: A
authors.lastname: Morgentaler
mesh_terms: D000368:Aged; D015331:Cohort Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading / Q000145:classification; D011159:Population Surveillance; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood* / Q000145:classification / Q000473:pathology*; D012372:ROC Curve; D013739:Testosterone / Q000097:blood*
chemical_list: D013739:Testosterone; D017430:Prostate-Specific Antigen
keywords: active surveillance; prostate cancer; testosterone