title: Predictive role of free prostate-specific antigen in a prospective active surveillance program (PRIAS).
abstract: OBJECTIVE
  To evaluate the utility of percentage of free serum PSA (%fPSA) as a predictor of adverse rebiopsy findings, treatment change and radical prostatectomy (RP) findings in a prospective active surveillance (AS) trial.
  
  
  METHODS
  Patients enrolled in the global PRIAS study with baseline %fPSA available were included. Putative baseline predictors (e.g. PSA, %fPSA) of adverse rebiopsy findings were explored using logistic regression analysis. Association of variables with treatment change and RP findings over time were evaluated with Cox regression analysis. Active treatment-free survival was assessed with a Kaplan-Meier method.
  
  
  RESULTS
  Of 3701 patients recruited to PRIAS, 939 had %fPSA measured at study entry. Four hundred and thirty-eight of them had %fPSA available after 1 year. Median follow-up was 17.2 months. First rebiopsy results were available for 595 patients and of those, 144 (24.2 %) had adverse findings. A total of 283 (30.1 %) patients discontinued surveillance, of those 181 (64.0 %) due to protocol-based reasons. Although median %fPSA values were significantly lower in patients who changed treatment, according to the multivariate regression analysis, initial %fPSA value was not predictive for treatment change or adverse rebiopsy findings. However, the probability of discontinuing AS was significantly lower in patients with "favourable" initial %fPSA characteristics and %fPSA during follow-up (initial %fPSA ≥15 and positive %fPSA velocity) compared to those with "adverse" %fPSA characteristics (initial %fPSA <15 and negative %fPSA velocity).
  
  
  CONCLUSIONS
  Diagnostic %fPSA provides no additional prognostic value when compared to other predictors already in use in AS protocols. However, %fPSA velocity during surveillance may aid in predicting the probability for future treatment change.
authors.affiliation: Department of Urology, Peijas Hospital, Helsinki University Central Hospital and University of Helsinki, P.O. Box 900, 00029, Helsinki, Finland. hanna.vasarainen@hus.fi.
authors.forename: Hanna
authors.initials: H
authors.lastname: Vasarainen
authors.affiliation: Department of Urology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Jolanda
authors.initials: J
authors.lastname: Salman
authors.affiliation: Department of Urology, Peijas Hospital, Helsinki University Central Hospital and University of Helsinki, P.O. Box 900, 00029, Helsinki, Finland.
authors.forename: Heidi
authors.initials: H
authors.lastname: Salminen
authors.affiliation: Department of Radiation Oncology 1, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Valdagni
authors.affiliation: Department of Radiation Oncology and Developmental Radiotherapeutics, University of British Columbia, and BC Cancer Agency, Vancouver, Canada.
authors.forename: Tom
authors.initials: T
authors.lastname: Pickles
authors.affiliation: Department of Urology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Chris
authors.initials: C
authors.lastname: Bangma
authors.affiliation: Department of Urology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Monique J
authors.initials: MJ
authors.lastname: Roobol
authors.affiliation: Department of Urology, Peijas Hospital, Helsinki University Central Hospital and University of Helsinki, P.O. Box 900, 00029, Helsinki, Finland.
authors.forename: Antti
authors.initials: A
authors.lastname: Rannikko
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood; D001706:Biopsy; D055088:Early Detection of Cancer / Q000379:methods*; D005500:Follow-Up Studies; D014943:Global Health; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods*; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000453:epidemiology / Q000473:pathology; D015996:Survival Rate / Q000639:trends; D013997:Time Factors
chemical_list: D014408:Biomarkers, Tumor; D017430:Prostate-Specific Antigen
keywords: Active surveillance; Free prostate-specific antigen; Prostate cancer; Prostate-specific antigen
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