title: Greater biopsy core number is associated with improved biochemical control in patients treated with permanent prostate brachytherapy.
abstract: OBJECTIVE
  Standard prostate biopsy schemes underestimate Gleason score in a significant percentage of cases. Extended biopsy improves diagnostic accuracy and provides more reliable prognostic information. In this study, we tested the hypothesis that greater biopsy core number should result in improved treatment outcome through better tailoring of therapy.
  
  
  METHODS
  From April 1995 to May 2006, 1,613 prostate cancer patients were treated with permanent brachytherapy. Patients were divided into five groups stratified by the number of prostate biopsy cores (≤6, 7-9, 10-12, 13-20, and >20 cores). Biochemical progression-free survival (bPFS), cause-specific survival (CSS), and overall survival (OS) were evaluated as a function of core number.
  
  
  RESULTS
  The median patient age was 66 years, and the median preimplant prostate-specific antigen was 6.5 ng/mL. The overall 10-year bPFS, CSS, and OS were 95.6%, 98.3%, and 78.6%, respectively. When bPFS was analyzed as a function of core number, the 10-year bPFS for patients with >20, 13-20, 10-12, 7-9 and ≤6 cores was 100%, 100%, 98.3%, 95.8%, and 93.0% (p < 0.001), respectively. When evaluated by treatment era (1995-2000 vs. 2001-2006), the number of biopsy cores remained a statistically significant predictor of bPFS. On multivariate analysis, the number of biopsy cores was predictive of bPFS but did not predict for CSS or OS.
  
  
  CONCLUSIONS
  Greater biopsy core number was associated with a statistically significant improvement in bPFS. Comprehensive regional sampling of the prostate may enhance diagnostic accuracy compared to a standard biopsy scheme, resulting in better tailoring of therapy.
authors.affiliation: Tacoma/Valley Radiation Oncology Centers, Tacoma, WA, USA.
authors.forename: Nathan
authors.initials: N
authors.lastname: Bittner
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Merrick
authors.forename: Robert W
authors.initials: RW
authors.lastname: Galbreath
authors.forename: Wayne M
authors.initials: WM
authors.lastname: Butler
authors.forename: Edward
authors.initials: E
authors.lastname: Adamovich
authors.forename: Kent E
authors.initials: KE
authors.lastname: Wallner
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D001707:Biopsy, Needle; D001918:Brachytherapy / Q000379:methods*; D018572:Disease-Free Survival; D006801:Humans; D008297:Male; D011467:Prostate / Q000473:pathology*; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood / Q000401:mortality / Q000473:pathology* / Q000532:radiotherapy*; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D017430:Prostate-Specific Antigen