title: Clinical evaluation of percent free prostate-specific antigen using the AxSYM system in the best analytical scenario.
abstract: OBJECTIVE
  Percent free prostate-specific antigen (PSA) is a promising tool for prostate cancer (CaP) diagnosis. However, its diagnostic performances have not yet been established. The present study was carried out with the aim of evaluating percent free PSA in the most favourable analytical conditions.
  
  
  METHODS
  Eighty-eight patients affected by newly diagnosed, untreated, primary CaP, and 169 cases with biopsy-confirmed, untreated, benign prostatic hypertrophy (BPH) were prospectively enrolled. Abbott AxSYM total and free PSA were measured by the same technician using the same instrument and the same reagent batch.
  
  
  RESULTS
  Percent free PSA was more effective than total PSA in differential diagnosis between CaP and BPH in every evaluated dose range of total PSA. In cases with total PSA >4 microg/l, percent free PSA could have reduced by about 50% the rate of unnecessary biopsies with a probably still acceptable 93% cancer detection rate. The likelihood of CaP after the determination of percent free PSA was in fact higher than 50% using cut-off points which provide low sensitivity values (i.e. 58% in men aged 50-59 years).
  
  
  CONCLUSIONS
  Percent free PSA is superior to total PSA in distinguishing primary CaP from BPH in patients with total PSA between 2 and 30 microg/l and in reducing the rate of unnecessary biopsies in men with total PSA higher than 4 microg/l. However, percent free PSA should be cautiously interpreted in decision making in individual patients since post-test probability is relatively low in men aged 50-70 years.
authors.affiliation: Centro Nazionale Applicazione Biotecnologie in Oncologia, Regional Hospital, Venice, Italy. cnabo@provincia,venezia.it
authors.forename: M
authors.initials: M
authors.lastname: Gion
authors.forename: R
authors.initials: R
authors.lastname: Mione
authors.forename: P
authors.initials: P
authors.lastname: Barioli
authors.forename: M
authors.initials: M
authors.lastname: Barichello
authors.forename: F
authors.initials: F
authors.lastname: Zattoni
authors.forename: T
authors.initials: T
authors.lastname: Prayer-Galetti
authors.forename: M
authors.initials: M
authors.lastname: Plebani
authors.forename: G
authors.initials: G
authors.lastname: Aimo
authors.forename: C
authors.initials: C
authors.lastname: Terrone
authors.forename: F
authors.initials: F
authors.lastname: Manferrari
authors.forename: G
authors.initials: G
authors.lastname: Madeddu
authors.forename: L
authors.initials: L
authors.lastname: Caberlotto
authors.forename: A
authors.initials: A
authors.lastname: Fandella
authors.forename: C
authors.initials: C
authors.lastname: Pianon
authors.forename: L
authors.initials: L
authors.lastname: Vianello
authors.forename: B
authors.initials: B
authors.lastname: Amoroso
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D001707:Biopsy, Needle; D003937:Diagnosis, Differential; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008875:Middle Aged; D011336:Probability; D011446:Prospective Studies; D017430:Prostate-Specific Antigen / Q000097:blood*; D011470:Prostatic Hyperplasia / Q000097:blood* / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000473:pathology*; D012372:ROC Curve; D012680:Sensitivity and Specificity
chemical_list: D017430:Prostate-Specific Antigen