title: Multicenter comparison of the diagnostic performance of free prostate-specific antigen.
abstract: OBJECTIVE
  This study examined the multicenter clinical performance of noncomplexed (free) prostate-specific antigen (PSA) in men presenting with total PSA values between 2.5 to 20 ng/mL.
  
  
  METHODS
  Prebiopsy serum samples were obtained from 1,081 consecutively accrued, histologically diagnosed men between the ages of 40 and 75 years with total PSA values falling between 2.5 and 20 ng/mL. Total PSA was determined by either the Tosoh AIA-1200 or Hybritech method. Free PSA values were determined using the Dianon PSA II immunoradiometric method. Free PSA was expressed as a percentage of total PSA. Immunochemistry was performed at each accrual site.
  
  
  RESULTS
  Among men diagnosed with prostate cancer (CaP), only 4% (21/520) had proportions of free to total PSA values > 25%. Conversely, among men with benign prostatic disease, only 2% (13/561) had proportions of free to total PSA values < 7%. These results confirm those of previous research. Differences among sites were found in age and prostate volume.
  
  
  CONCLUSIONS
  These data confirm that free PSA values < 7% are highly suspicious for CaP whereas free PSA values > 25% suggest absence of malignancy. The data also suggest that age and/or prostate volume influences the serum level of free PSA but does not affect the diagnostic cutoff points of 7% and 25%. Future analysis is needed to confirm that younger men with small prostates are at higher risk for CaP.
authors.affiliation: Dianon Systems, Inc., Stratford, CT 06497, USA.
authors.forename: R P
authors.initials: RP
authors.lastname: Thiel
authors.forename: J E
authors.initials: JE
authors.lastname: Oesterling
authors.forename: K J
authors.initials: KJ
authors.lastname: Wojno
authors.forename: A W
authors.initials: AW
authors.lastname: Partin
authors.forename: D W
authors.initials: DW
authors.lastname: Chan
authors.forename: H B
authors.initials: HB
authors.lastname: Carter
authors.forename: T A
authors.initials: TA
authors.lastname: Stamey
authors.forename: A R
authors.initials: AR
authors.lastname: Prestigiacomo
authors.forename: M K
authors.initials: MK
authors.lastname: Brawer
authors.forename: J C
authors.initials: JC
authors.lastname: Petteway
authors.forename: G
authors.initials: G
authors.lastname: Carlson
authors.forename: A A
authors.initials: AA
authors.lastname: Luderer
mesh_terms: D000328:Adult; D000368:Aged; D006801:Humans; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood / Q000175:diagnosis*
chemical_list: D017430:Prostate-Specific Antigen