title: Significance of free to total PSA ratio in men with slightly elevated serum PSA levels: a cooperative study.
abstract: BACKGROUND
  The ratio of free PSA in total PSA (f/t) has been reported to improve the diagnostic accuracy of prostate cancer in the group with slightly elevated serum PSA values. In Japanese cases, the clinical significance of f/t is still controversial.
  
  
  METHODS
  The diagnostic significance of f/t in serum for prostate cancer was evaluated in a cooperative study. A total of 77 cases with prostate cancer and 224 with non-prostate cancer showing less than 20 ng/ml of total PSA were evaluated.
  
  
  RESULTS
  Serum total and free PSA values were not affected by storage at 25 degrees C for 2 days. The determination of f/t was useful in the cases with a serum total PSA of 5.1-10 ng/ml; the specificity was 60% with a sensitivity of 90% at an f/t of 0.148. The positive predictive value for diagnosis of prostate cancer also increased to 54% from 34% of that in total PSA alone. In the range of 4.1-10 ng/ml, the cut-off value of f/t was 0.155 for obtaining relatively high specificity; sensitivity was 85% and specificity was 56.5%.
  
  
  CONCLUSIONS
  Thus, the determination of f/t was considered to be an effective tool for discriminating the non-prostate cancer cases from those of prostate cancer.
authors.affiliation: Department of Urology, Gifu University School of Medicine, Japan. mkuriyam-gif@umin.u-tokyo.ac.jp
authors.forename: M
authors.initials: M
authors.lastname: Kuriyama
authors.forename: Y
authors.initials: Y
authors.lastname: Kawada
authors.forename: Y
authors.initials: Y
authors.lastname: Arai
authors.forename: H
authors.initials: H
authors.lastname: Maeda
authors.forename: S
authors.initials: S
authors.lastname: Egawa
authors.forename: K
authors.initials: K
authors.lastname: Koshiba
authors.forename: K
authors.initials: K
authors.lastname: Imai
authors.forename: H
authors.initials: H
authors.lastname: Yamanaka
mesh_terms: D006801:Humans; D008297:Male; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000175:diagnosis*; D012680:Sensitivity and Specificity
chemical_list: D017430:Prostate-Specific Antigen