title: Clinical utility of the percentage of positive prostate biopsies in predicting prostate cancer-specific and overall survival after radiotherapy for patients with localized prostate cancer.
abstract: OBJECTIVE
  To determine whether the percentage of positive prostate biopsies provides clinically relevant information to a previously established risk stratification system with respect to the end points of prostate cancer-specific survival (PCSS) and overall survival after radiotherapy for patients with clinically localized prostate cancer.
  
  
  METHODS
  A Cox regression multivariable analysis was used to evaluate the ability of the percentage of positive prostate biopsies to predict PCSS and overall survival for 381 men who underwent radiotherapy for localized prostate cancer during the prostate-specific antigen era.
  
  
  RESULTS
  At a median follow-up of 4.3 years (range 0.8-13.3), the presence of < or =50% positive biopsies vs. >50% positive biopsies provided a clinically relevant stratification of the 7-year estimates of PCSS (100% vs. 57%, p = 0.004) in intermediate-risk patients. Moreover, all patients could be stratified into a minimal or high-risk cohort on the basis of the 10-year estimates of PCSS (100% vs. 55%, p <0.0001) and overall survival (87% vs. 40%, p = 0.02) by incorporating the percentage of positive prostate biopsy information into a previously established risk stratification system.
  
  
  CONCLUSIONS
  The clinically relevant stratification of PCSS using the percentage of positive prostate biopsies in intermediate-risk patients confirms previous findings based on prostate-specific antigen outcome. These data provide evidence to support the ability to stratify newly diagnosed patients with clinically localized disease into a minimal-risk (low-risk + low biopsy volume [< or =50%] intermediate-risk) or high-risk (high biopsy volume [>50%] intermediate-risk + high-risk) cohort for prostate cancer-specific death after conventional dose radiotherapy. Additional follow-up and independent validation are needed to confirm these findings.
authors.affiliation: Department of Radiation Oncology, Brigham and Women's Hospital, 75 Francis Street, L-2 Level, Boston, MA 02215, USA. adamico@roc.harvard.edu
authors.forename: Anthony V
authors.initials: AV
authors.lastname: D'Amico
authors.forename: Aparna
authors.initials: A
authors.lastname: Keshaviah
authors.forename: Judith
authors.initials: J
authors.lastname: Manola
authors.forename: Kerri
authors.initials: K
authors.lastname: Cote
authors.forename: Marian
authors.initials: M
authors.lastname: Loffredo
authors.forename: Olga
authors.initials: O
authors.lastname: Iskrzytzky
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Renshaw
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016016:Proportional Hazards Models; D011467:Prostate / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000401:mortality* / Q000473:pathology* / Q000532:radiotherapy; D018570:Risk Assessment