title: Is prostate-specific antigen percentage decrease predictive of clinical outcome after permanent iodine-125 interstitial brachytherapy for prostate cancer?
abstract: OBJECTIVE
  To determine the usefulness of prostate-specific antigen (PSA) percentage (vs. pretreatment value assumed as 100%) in prediction of biochemical relapse, after iodine-125 ((125)I) permanent brachytherapy for prostate cancer, to employ a parameter independent by the initial PSA amount and by the individual prostatic volume.
  
  
  METHODS
  Our study included 133 patients, 102 still disease free (Group A) and 31 who experienced proven biochemical recurrence (Group B). PSA levels before and after (125)I brachytherapy were recorded, and PSA percentage vs. pretreatment values were calculated. Cox regression model, receiver operating characteristic curves, and Kaplan-Meier regression model with log-rank test were calculated.
  
  
  RESULTS
  We observed that, in patients submitted to brachytherapy for prostate cancer, a PSA percentage >20% of pretreatment value is highly associated with relapse risk (p<0.0001) and that this association is strongly present since t=6 months of followup (p<0.0001), with a hazard ratio near to five times (4.965), a sensitivity of 72.4%, and specificity of 79.8% related to the chosen cutoff.
  
  
  CONCLUSIONS
  Despite the amount of PSA is the only parameter that the clinicians can deploy to monitor patient's followup after permanent interstitial brachytherapy for prostate cancer, its evolution in time seems unable to predict early biochemical relapse as it is influenced by prostatic volume and initial PSA amount.
  
  
  CONCLUSIONS
  Our data suggest that a PSA percentage >20% of pretreatment value at 6 months might represent an early, inexpensive, and useful predictive tool of bad outcome in patients after permanent brachytherapy.
authors.affiliation: Operative Unit of Urology, Campo di Marte Hospital, ASL 2 Lucca, Italy. mpaoluzzi@usl2.toscana.it
authors.forename: Mauro
authors.initials: M
authors.lastname: Paoluzzi
authors.forename: Marcello
authors.initials: M
authors.lastname: Mignogna
authors.forename: Elena
authors.initials: E
authors.lastname: Lorenzini
authors.forename: Francesca
authors.initials: F
authors.lastname: Valent
authors.forename: Nicola
authors.initials: N
authors.lastname: Fontana
authors.forename: Novello
authors.initials: N
authors.lastname: Pinzi
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Repetti
authors.forename: Roberto
authors.initials: R
authors.lastname: Ponchietti
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood*; D001918:Brachytherapy / Q000706:statistics & numerical data*; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D009364:Neoplasm Recurrence, Local / Q000097:blood* / Q000453:epidemiology / Q000517:prevention & control*; D017063:Outcome Assessment, Health Care / Q000379:methods / Q000706:statistics & numerical data; D015995:Prevalence; D011379:Prognosis; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000453:epidemiology / Q000532:radiotherapy*; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity
chemical_list: D014408:Biomarkers, Tumor; D017430:Prostate-Specific Antigen