title: Postoperative nomogram predicting the 9-year probability of prostate cancer recurrence after permanent prostate brachytherapy using radiation dose as a prognostic variable.
abstract: OBJECTIVE
  To report a multi-institutional outcomes study on permanent prostate brachytherapy (PPB) to 9 years that includes postimplant dosimetry, to develop a postimplant nomogram predicting biochemical freedom from recurrence.
  
  
  METHODS
  Cox regression analysis was used to model the clinical information for 5,931 patients who underwent PPB for clinically localized prostate cancer from six centers. The model was validated against the dataset using bootstrapping. Disease progression was determined using the Phoenix definition. The biological equivalent dose was calculated from the minimum dose to 90% of the prostate volume (D90) and external-beam radiotherapy dose using an alpha/beta of 2.
  
  
  RESULTS
  The 9-year biochemical freedom from recurrence probability for the modeling set was 77% (95% confidence interval, 73-81%). In the model, prostate-specific antigen, Gleason sum, isotope, external beam radiation, year of treatment, and D90 were associated with recurrence (each p < 0.05), whereas clinical stage was not. The concordance index of the model was 0.710.
  
  
  CONCLUSIONS
  A predictive model for a postimplant nomogram for prostate cancer recurrence at 9-years after PPB has been developed and validated from a large multi-institutional database. This study also demonstrates the significance of implant dosimetry for predicting outcome. Unique to predictive models, these nomograms may be used a priori to calculate a D90 that likely achieves a desired outcome with further validation. Thus, a personalized dose prescription can potentially be calculated for each patient.
authors.affiliation: Department of Radiation Medicine, North Shore Long Island Jewish Health System, 270-05 76th Ave., New Hyde Park, NY 11040, USA. LPotters@nshs.edu
authors.forename: Louis
authors.initials: L
authors.lastname: Potters
authors.forename: Mack
authors.initials: M
authors.lastname: Roach
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Davis
authors.forename: Richard G
authors.initials: RG
authors.lastname: Stock
authors.forename: Jay P
authors.initials: JP
authors.lastname: Ciezki
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Zelefsky
authors.forename: Nelson N
authors.initials: NN
authors.lastname: Stone
authors.forename: Paul A
authors.initials: PA
authors.lastname: Fearn
authors.forename: Changhong
authors.initials: C
authors.lastname: Yu
authors.forename: Katsuto
authors.initials: K
authors.lastname: Shinohara
authors.forename: Michael W
authors.initials: MW
authors.lastname: Kattan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy / Q000379:methods*; D018450:Disease Progression; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000097:blood / Q000175:diagnosis*; D049451:Nomograms; D011336:Probability; D011379:Prognosis; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D012044:Regression Analysis
chemical_list: D017430:Prostate-Specific Antigen