title: Optimized prostate brachytherapy minimizes the prognostic impact of percent of biopsy cores involved with adenocarcinoma.
abstract: OBJECTIVE
  A higher percent of positive biopsy cores predicts poor biochemical failure-free survival. The highest dose covering at least 90% of the prostate is a standard method of measuring implant quality. We tested the hypothesis that the percentage of positive biopsy cores loses its adverse prognostic impact in patients who receive implants with a highest dose covering at least 90% of the prostate of 100% or greater of the prescription dose.
  
  
  METHODS
  A total of 568 patients with intermediate to high risk adenocarcinoma of the prostate who were previously treated with brachytherapy in a prospective, randomized study were evaluated. The relationship between the percentage of positive biopsy cores, the highest dose covering at least 90% of the prostate and biochemical failure was examined.
  
  
  RESULTS
  At a median followup of 50 months the rate of 5-year biochemical failure-free survival was 87% for the entire group and 92% vs 81% for patients with less than 50% vs 50% or greater positive biopsy cores (log rank p = 0.009). The mean highest dose covering at least 90% of the prostate was statistically lower in failing vs nonfailing cases (p = 0.03). Gleason score, prostate specific antigen, 50% or greater positive biopsy cores and the highest dose covering at least 90% of the prostate were the only statistically significant predictive factors for biochemical failure-free survival on multivariate Cox regression analysis. When regression analysis was restricted to the 237 patients who received implants with a highest dose covering at least 90% of the prostate of 100% or greater, 50% or greater positive biopsy cores lost predictive value but prostate specific antigen and Gleason score remained independent prognostic factors.
  
  
  CONCLUSIONS
  A total of 50% or greater positive biopsy cores is an independent predictor of poor biochemical failure-free survival in patients treated with brachytherapy. High quality prostate brachytherapy, defined by a highest dose covering at least 90% of the prostate of 100% or greater, minimize the adverse effect of 50% or greater positive biopsy cores on time to biochemical failure.
authors.affiliation: Department of Radiation Oncology, Puget Sound Health Care System, Seattle, Washington 98108-1597, USA. riz@u.washington.edu
authors.forename: Rizwan
authors.initials: R
authors.lastname: Nurani
authors.forename: Kent
authors.initials: K
authors.lastname: Wallner
authors.forename: Gregory
authors.initials: G
authors.lastname: Merrick
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Virgin
authors.forename: Peter
authors.initials: P
authors.lastname: Orio
authors.forename: Lawrence D
authors.initials: LD
authors.lastname: True
mesh_terms: D000230:Adenocarcinoma / Q000097:blood / Q000473:pathology / Q000532:radiotherapy*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy / Q000379:methods / Q000592:standards*; D018572:Disease-Free Survival; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D011446:Prospective Studies; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000473:pathology / Q000532:radiotherapy*; D011879:Radiotherapy Dosage / Q000592:standards; D012307:Risk Factors
chemical_list: D017430:Prostate-Specific Antigen