title: The correlation between annular treatment margins and biochemical failure in prostate brachytherapy patients with optimized intraprostatic dosimetry.
abstract: OBJECTIVE
  To determine whether periprostatic treatment margins correlate with biochemical control in prostate brachytherapy patients with optimized intraprostatic dosimetry.
  
  
  METHODS
  Nineteen biochemically failed brachytherapy patients were matched to 74 dosimetric and clinically equivalent nonfailures. The median followup time for the entire study population was 9.4 years. Eligibility requirements included a Day 0 intraprostatic D(90) of 100% or greater and V(100) of 90% or greater, absence of androgen deprivation therapy, and no evidence of distant metastasis in biochemically failed patients. A 5-mm annulus was constructed around the perimeter of each prostate. D(90) and V(100) at the anterior, posterior, superior, inferior, right lateral, and left lateral aspects of the annulus were evaluated for patients with biochemically controlled and failed disease. Biochemical progression-free survival (bPFS) was defined as a prostate-specific antigen level of 0.40ng/mL or less after nadir. D(90) and V(100) parameters were compared between the controlled and failed groups using logistic regression. Predictors of biochemical failure were identified using Cox regression.
  
  
  RESULTS
  No statistically significant differences in prostate-specific antigen level, Gleason score, percent positive biopsies, or intraprostatic dosimetry were observed between the controlled and failed patients. The D(90) and V(100) at the anterior, posterior, superior, inferior, right lateral, and left lateral aspects of the annulus were not statistically different between biochemically controlled and failed groups.
  
  
  CONCLUSIONS
  In this study, there was no relationship observed between annular dosimetry and biochemical control. It is unlikely that further radial dose intensification would have altered treatment outcome in this population of patients with optimized intraprostatic dosimetry.
authors.affiliation: Tacoma/Valley Radiation Oncology Centers, Tacoma, WA.
authors.forename: Nathan
authors.initials: N
authors.lastname: Bittner
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Merrick
authors.forename: Wayne M
authors.initials: WM
authors.lastname: Butler
authors.forename: Zachariah A
authors.initials: ZA
authors.lastname: Allen
authors.forename: Brittany
authors.initials: B
authors.lastname: White
authors.forename: Ashley
authors.initials: A
authors.lastname: Adamovich
authors.forename: Kent E
authors.initials: KE
authors.lastname: Wallner
mesh_terms: D000368:Aged; D001918:Brachytherapy / Q000379:methods*; D018572:Disease-Free Survival; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000532:radiotherapy*; D011879:Radiotherapy Dosage
chemical_list: D017430:Prostate-Specific Antigen