To determine whether a previously reported substratification system can be extrapolated to patients with high-risk prostate cancer treated with permanent interstitial brachytherapy.
Four hundred six National Comprehensive Cancer Network patients with high-risk prostate cancer treated with permanent prostate brachytherapy with or without supplemental external beam radiotherapy were stratified into good (prostate-specific antigen >20 or Gleason score ≥8 or ≥T3), intermediate (prostate-specific antigen >20 and ≥T3), and poor (Gleason score ≥8 with ≥1 additional high-risk feature) prognostic cohorts.