The role of external beam irradiation in patients undergoing prostate brachytherapy

The role of external beam irradiation (EBT) combined with transperineal int erstitial permanent prostate brachytherapy (TIPPB) re main undefined. There fore, the purpose of this study was to evaluate the role of EBT when combin ed with TIPPB in a retrospective, matched-pair analysis. Between September 1992 and January 1997, 605 consecutive patients with clinically localized p rostate cancer underwent TIPPB. Patients with prostate specific antigen (PS A) levels less than or equal to 10, Gleason scores less than or equal to 6, and stage less than or equal to T2a underwent TIPPB alone using I-125 and Pd-103 [160 Cy (pre-TG-43) and 120 Gy, respectively]. Combined EBT and TIPP B was offered to patients with a PSA level >10 and/or Gleason score >6. Fro m this cohort, a matched-pair analysis was performed to better assess the r ole of EBT and TIPPB (n = 215). PSA relapse-free survival was based on the American Society for Therapeutic Radiology and Oncology Consensus Panel def inition. Kaplan-Meier actuarial survival curves were compared to assess var ious prognostic factors. The median follow-up for all 215 matched patients was 44 months (range, 24-81) with an actuarial PSA relapse-free survival (R FS) at 5 years of 81.1%. Patients treated with EBT and TIPPB had a 5-year P SA RFS of 83.5% whereas patients treated with TIPPB only had a 5-year PSA R FS of 79.4% (p = 0.715). There was no difference in outcome between groups with regard to Gleason score groupings or PSA less than or equal to 10 ng/m l or >10 ng/ml. Risk group analysis combining PSA, Gleason score, and stage failed to identify any risk group for which the addition of EBT was signif icant. Analysis of postimplant dosimetry using the dose to 90% of the prost ate volume (D90) failed to distinguish anp difference between groups. A sig nificant advantage for combining EBT and TIPPB could not be demonstrated in this retrospective matched-pair analysis. These data indicate that the rol e and rationale of combined treatment in prostate brachytherapy requires be tter clarification, with a prospective randomized trial. (C) 2000 Elsevier Science Inc. All rights reserved.