title: Prostate-specific antigen (PSA) kinetics in untreated, localized prostate cancer: PSA velocity vs PSA doubling time.
abstract: OBJECTIVE
  To compare the accuracy of prostate-specific antigen (PSA) velocity (PSAV) vs PSA doubling time (DT) for predicting the repeat biopsy results in men with localized prostate cancer on active surveillance (AS), as the utility of PSAV vs PSADT in untreated prostate cancer has not been well studied.
  
  
  METHODS
  Eligible patients had favourable-risk localized prostate cancer (T1/2a, PSA level <or=15 ng/mL, Gleason score <or=3 + 4, and percentage positive biopsy cores <or=50%), and consented to AS between 2002 and 2005. Repeat biopsies were taken after 18-24 months, with adverse histology defined as any of: primary Gleason grade >or=4, >50% cores positive, or initial Gleason score 3 + 3 upgraded to >or=3 + 4. Using all PSA values for the 2 years preceding repeat biopsy, the PSAV and PSADT were calculated using linear regression and the log-slope method (DT = ln2/slope), respectively.
  
  
  RESULTS
  In all, 199 patients were assessable; the median PSAV and PSADT were 0.71 ng/mL/year and 5.29 years, respectively. Fifty-three patients (27%) had adverse histology on repeat biopsy. On univariate analyses, PSAV (P < 0.001) and PSADT (P = 0.019) were associated with adverse histology. The area under the receiver operating characteristic curve for predicting adverse histology was 0.70 and 0.63 for PSAV and PSADT, respectively. The mean difference was 0.07 (95% confidence interval 0.03-0.12; P < 0.001).
  
  
  CONCLUSIONS
  PSAV is more accurate than PSADT for predicting adverse histology on repeat biopsies. These data suggest that PSAV should be used in preference to PSADT to describe PSA kinetics in untreated, localized prostate cancer.
authors.affiliation: Academic Unit Urology, Royal Marsden Hospital, Sutton, UK. michael.ng@petermac.org
authors.forename: Michael K
authors.initials: MK
authors.lastname: Ng
authors.forename: Nicholas
authors.initials: N
authors.lastname: Van As
authors.forename: Karen
authors.initials: K
authors.lastname: Thomas
authors.forename: Ruth
authors.initials: R
authors.lastname: Woode-Amissah
authors.forename: Alan
authors.initials: A
authors.lastname: Horwich
authors.forename: Robert
authors.initials: R
authors.lastname: Huddart
authors.forename: Vincent
authors.initials: V
authors.lastname: Khoo
authors.forename: Alan
authors.initials: A
authors.lastname: Thompson
authors.forename: David
authors.initials: D
authors.lastname: Dearnaley
authors.forename: Chris
authors.initials: C
authors.lastname: Parker
mesh_terms: D000368:Aged; D019540:Area Under Curve; D001706:Biopsy; D018450:Disease Progression; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D011467:Prostate / Q000473:pathology*; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood / Q000473:pathology*; D012372:ROC Curve; D012044:Regression Analysis
chemical_list: D017430:Prostate-Specific Antigen