title: The clinical utility of the percent of positive prostate biopsies in predicting biochemical outcome following external-beam radiation therapy for patients with clinically localized prostate cancer.
abstract: OBJECTIVE
  An investigation was performed of the clinical utility of the percent of positive prostate biopsies in predicting prostate-specific antigen (PSA) outcome following external-beam radiation therapy (RT) for men with PSA-detected or clinically palpable prostate cancer.
  
  
  METHODS
  A Cox regression multivariable analysis was used to determine whether the percent of positive prostate biopsies provided clinically relevant information about PSA outcome following external beam RT in 473 men while accounting for the previously established risk groups based on the pretreatment PSA level, biopsy Gleason score, and the 1992 American Joint Commission on Cancer (AJCC) clinical T stage.
  
  
  RESULTS
  Controlling for the known prognostic factors, the percent of positive prostate biopsies added clinically significant information (p = 0.02) regarding time to PSA failure following RT. Specifically, 76% of the patients in the intermediate risk group (1992 AJCC T(2b) or biopsy Gleason 7 or PSA > 10 ng/mL and < or = 20 ng/mL) could be classified into either an 30% or 85% 5-year PSA control cohort using the preoperative prostate biopsy data.
  
  
  CONCLUSIONS
  The previously validated stratification of PSA outcome following radical prostatectomy (RP) using the percent of positive prostate biopsies in intermediate-risk patients is also clinically significant for men treated with external beam RT. The percent positive prostate biopsies should be considered in conjunction with the PSA level, biopsy Gleason score, and 1992 AJCC clinical T stage when counseling patients with newly diagnosed and clinically localized prostate cancer about PSA outcome following RP or external beam RT.
authors.affiliation: Joint Center for Radiation Therapy, Harvard Medical School, Boston, MA, USA. adamico@jcrt.harvard.edu
authors.forename: A V
authors.initials: AV
authors.lastname: D'Amico
authors.forename: D
authors.initials: D
authors.lastname: Schultz
authors.forename: B
authors.initials: B
authors.lastname: Silver
authors.forename: L
authors.initials: L
authors.lastname: Henry
authors.forename: M
authors.initials: M
authors.lastname: Hurwitz
authors.forename: I
authors.initials: I
authors.lastname: Kaplan
authors.forename: C J
authors.initials: CJ
authors.lastname: Beard
authors.forename: A A
authors.initials: AA
authors.lastname: Renshaw
mesh_terms: D001706:Biopsy; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D009367:Neoplasm Staging; D011379:Prognosis; D016016:Proportional Hazards Models; D011467:Prostate / Q000473:pathology*; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000473:pathology* / Q000532:radiotherapy; D020266:Radiotherapy, Conformal
chemical_list: D017430:Prostate-Specific Antigen