title: Time from first detectable PSA following radical prostatectomy to biochemical recurrence: A competing risk analysis.
abstract: BACKGROUND
  In this study, we estimated the time from first detectable prostate-specific antigen (PSA) following radical prostatectomy (RP) to commonly used definitions of biochemical recurrence (BCR). We also identified the predictors of time to BCR.
  
  
  METHODS
  We identified subjects who underwent a RP and had an undetectable PSA after surgery followed by at least 1 detectable PSA between 2000 and 2011. The primary outcome was time to BCR (PSA ≥0.2 and successive PSA ≥0.2) and prediction of the rate of PSA rise. Outcomes were calculated using a competing risk analysis, with univariable and multivariable Fine and Grey models. We employed a mixed effect model to test clinical predictors that are associated with the rate of PSA rise.
  
  
  RESULTS
  The cohort included 376 patients. The median follow-up from surgery was 60.5 months (interquartile range [IQR] 40.8-91.5) and from detectable PSA was 18 months (IQR 11-32). Only 45.74% (n = 172) had PSA values ≥0.2 ng/mL, while 15.16% (n = 57) reached the PSA level of ≥0.4 ng/mL and rising. On multivariable analysis, the values of the first detectable PSA and pathologic Gleason grade 8 or higher were consistently independent predictors of time to BCR. In the mixed effect model rate, the PSA rise was associated with time from surgery to first detectable PSA, Gleason score, and prostate volume. The main limitation of this study is the large proportion of patients that received treatment without reaching BCR. It is plausible that shorter estimated median times would occur at a centre that does not use salvage therapy at such an early state.
  
  
  CONCLUSIONS
  The time from first detectable PSA to BCR may be lengthy. Our analyses of the predictors of the rate of PSA rise can help determine a personalized approach for patients with a detectable PSA after surgery.
authors.affiliation: Division of Urology, Department of Surgical Oncology,University Health Network, Toronto, ON and Erasmus MC-beurs, Erasmus University Rotterdam, Netherlands;
authors.forename: Leonora
authors.initials: L
authors.lastname: de Boo
authors.affiliation: Clinical Study Coordination and Biostatistics, University Health Network, Toronto, ON;
authors.forename: Melania
authors.initials: M
authors.lastname: Pintilie
authors.affiliation: Laboratory Medicine Program, University Health Network, Toronto, ON;
authors.forename: Paul
authors.initials: P
authors.lastname: Yip
authors.affiliation: Division of Urology, Rabin Medical Center and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel;
authors.forename: Jack
authors.initials: J
authors.lastname: Baniel
authors.affiliation: Division of Urology, Department of Surgical Oncology, University Health Network, Toronto, ON;
authors.forename: Neil
authors.initials: N
authors.lastname: Fleshner
authors.affiliation: Division of Urology and Davidoff Cancer Center, Rabin Medical Center, Beilinson Hospital, Israel.
authors.forename: David
authors.initials: D
authors.lastname: Margel