title: Percentage of positive prostate biopsies independently predicts biochemical outcome following radiation therapy for prostate cancer.
abstract: BACKGROUND
  This work aims to definitely show the ability of percentage of positive biopsy cores (%PC) to independently predict biochemical outcome beyond traditional pretreatment risk-factors in prostate cancer (PCa) patients treated with radiotherapy.
  
  
  METHODS
  A cohort of 2493 men belonging to the EUREKA-2 retrospective multicentric database on (PCa) and treated with external-beam radiation therapy (EBRT) as primary treatment comprised the study population (median follow-up 50 months). A Cox regression time to prostate-specific antigen (PSA) failure analysis was performed to evaluate the predictive power of %PC, both in univariate and multivariate settings, with age, pretreatment PSA, clinical-radiological staging, bioptic Gleason Score (bGS), RT dose and RT +/- ADT as covariates.
  
  
  RESULTS
  P statistics for %PC is lower than 0.001 both in univariate and multivariate models. %PC as a continuous variable yields an AUC of 69% in ROC curve analysis for biochemical relapse. Four classes of %PC (1-20%, 21-50%, 51-80% and 81-100%) distinctly split patients for risk of biochemical relapse (overall log-rank test P<0.0001), with biochemical progression free survival (bPFS) at 5-years ranging from 88% to 58% and 10-years bPFS ranging from 80% to 38%.
  
  
  CONCLUSIONS
  We strongly affirm the usefulness of %PC information beyond main risk factors (PSA, staging and bGS) in predicting biochemical recurrence after EBRT for PCa. The stratification of patients according to %PC may be valuable to further discriminate cases with favourable or adverse prognosis.
authors.affiliation: Neuroscience Department, Human Physiology Section University of Torino, Turin, Italy - gabrielepda@alice.it.
authors.forename: Domenico
authors.initials: D
authors.lastname: Gabriele
authors.forename: Monica
authors.initials: M
authors.lastname: Garibaldi
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Girelli
authors.forename: Stefano
authors.initials: S
authors.lastname: Taraglio
authors.forename: Eleonora
authors.initials: E
authors.lastname: Duregon
authors.forename: Pietro
authors.initials: P
authors.lastname: Gabriele
authors.forename: Caterina
authors.initials: C
authors.lastname: Guiot
authors.forename: Enrico
authors.initials: E
authors.lastname: Bollito
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D016016:Proportional Hazards Models; D011467:Prostate / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D012189:Retrospective Studies