title: Using proportions of free to total prostate-specific antigen, age, and total prostate-specific antigen to predict the probability of prostate cancer.
abstract: OBJECTIVE
  This study was undertaken to define the probability of prostate cancer as a function of the proportion of free to total prostate-specific antigen (FTPSA), total PSA, and age for those patients with total PSA levels between 2.5 and 20.0 ng/mL.
  
  
  METHODS
  Prebiopsy serums were obtained from 428 untreated patients (165 malignant, 263 benign) who had undergone sextant six-core biopsy. Each patient had no prior history of prostate cancer and a prebiopsy total PSA value between 2.5 and 20.0 ng/mL. Total PSA levels were determined using the PA immunoassay performed on the TOSOH AIA-1200 automated immunoassay instrument. Free PSA levels were determined using a monoclonal-polyclonal antibody sandwich radioimmunoassay.
  
  
  RESULTS
  In men with total PSA values between 2.5 and 20.0 ng/mL, the FTPSA significantly differentiated between patients with benign and malignant histologic states. Log linear modeling indicated distinct differences in the risk for cancer as a function of FTPSA, total PSA, and age. The highest probability for cancer was observed in men greater than 70 years of age who had a FTPSA less than 7% and total PSA more than 10.0 ng/mL. Conversely, the lowest probability for cancer was observed in patients less than 60 years of age who had a FTPSA more than 25% and a total PSA less than 4 ng/mL.
  
  
  CONCLUSIONS
  The probability that prostate cancer will be found on biopsy has a marked gradient that is associated with age, total PSA, and FTPSA. The extreme ends of FTPSA of less than 7% and more than 25% are diagnostic for prostate cancer and benign prostatic disease, respectively.
authors.affiliation: Department of Research and Development, DIANON Systems, Inc., Stratford, Connecticut 06497, USA.
authors.forename: Y T
authors.initials: YT
authors.lastname: Chen
authors.forename: A A
authors.initials: AA
authors.lastname: Luderer
authors.forename: R P
authors.initials: RP
authors.lastname: Thiel
authors.forename: G
authors.initials: G
authors.lastname: Carlson
authors.forename: C L
authors.initials: CL
authors.lastname: Cuny
authors.forename: T F
authors.initials: TF
authors.lastname: Soriano
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D006801:Humans; D007118:Immunoassay; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D017430:Prostate-Specific Antigen / Q000097:blood*; D011470:Prostatic Hyperplasia / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood* / Q000175:diagnosis; D012372:ROC Curve; D012680:Sensitivity and Specificity
chemical_list: D017430:Prostate-Specific Antigen