title: [The usefulness of percentage of free prostate specific antigen/prostate specific antigen density in the diagnosis of prostate cancer].
abstract: OBJECTIVE
  To investigate the usefulness of percentage of free prostate specific antigen (FPSA/TPSA) in serum/PSA density [(F/T)/PSAD] in the diagnosis of prostate cancer.
  
  
  METHODS
  Two hundred and four patients who had been carried out transrectal ultrasound guided prostate biopsy, were involved in this study. Among them, 90 patients were proved to be suffering from prostate cancer, and other 114 patients were identified as benign prostate hypertrophy. The effect of total serum PSA level, FPSA/TPSA, PSAD and (F/T)/PSAD in the diagnosis of prostate cancer were investigated, and at the same time, selecting patients who should be carried out a prostate biopsy.
  
  
  RESULTS
  The mean values of (F/T)/PSAD were significantly lower for patients with prostate cancer in different PSA levels (<4.0, 4.0-, 10.1-, >20.0 microg/L), when compared with benign prostate hypertrophy patients. This difference has arrived statistical significance (P < 0.05). (F/T)/PSAD could provide higher specificity for diagnosing prostate cancer than FPSA/TPSA or PSAD. Among all patients, at the same higher sensitivity (about 90%), the specificity of FPSA/TPSA, PSAD and (F/T)/PSAD was 31.6%, 45.6% and 64.0%, respectively. At the same time, it was suggested that clinicians use different cutoffs for (F/T)/PSAD in different PSA level. When PSA level of patients was no more than 4.0 microg/L, 2.5 as the commended cutoff for (F/T)/PSAD was preferred; if PSA level was between 4.0 microg/L and 20.0 microg/L, 0.8 was a more suitable cutoff; 0.5 also could be taken as an appropriate cutoff in case of PSA level being higher than 20.0 microg/L.
  
  
  CONCLUSIONS
  Keeping high sensitivity, using of (F/T)/PSAD can improve the diagnostic specificity of prostate cancer significantly.
authors.affiliation: Department of Urology, General Hospital of People's Liberation Army, Beijing 100853, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Han
authors.forename: Jiang-ping
authors.initials: JP
authors.lastname: Gao
authors.forename: Xi-liang
authors.initials: XL
authors.lastname: Cao
authors.forename: Bao-fa
authors.initials: BF
authors.lastname: Hong
authors.forename: Jie
authors.initials: J
authors.lastname: Tang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D006801:Humans; D008297:Male; D008875:Middle Aged; D011467:Prostate / Q000473:pathology; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000175:diagnosis* / Q000473:pathology; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D017430:Prostate-Specific Antigen