Multi-institutional Evaluation of Elective Nodal Irradiation and/or Androgen Deprivation Therapy with Postprostatectomy Salvage Radiotherapy for Prostate Cancer

Background: Outcomes with postprostatectomy salvage radiation therapy (SRT) are not ideal. Little evidence exists regarding potential benefits of adding whole pelvic radiation therapy (WPRT) alone or in combination with androgen deprivation therapy (ADT). Objective: To explore whether WPRT and/or ADT added to prostate bed radiation therapy (PBRT) improves freedom from biochemical failure (FFBF) or distant metastases (DM). Design, setting, and participants: A database was compiled from 10 academic institutions of patients with postprostatectomy prostate-specific antigen (PSA) >0.01 ng/ml; pT1-4, Nx/0, cM0; and Gleason score (GS) ≥7 treated between 1987 and 2013. Median follow-up was 51 mo. Interventions: WPRT and/or ADT in addition to PBRT. Outcome measurements and statistical analyses: FFBF and DM were calculated using cumulative incidence estimation. Multivariable analysis (MVA) utilized cumulative incidence regression. Results and limitation: Median pre-SRT PSA was 0.5 ng/ml for 1861 patients. Median follow-up for patients not experiencing biochemical failure (BF) was 55 mo. MVA showed increased BF for PBRT versus WPRT (hazard ratio [HR] 1.82, p < 0.001) and no ADT versus ADT (HR 1.70, p < 0.001). WPRT was associated with a 5-yr FFBF of 62% versus 49% (p < 0.001) for PBRT. ADT use was associated with improved 5-yr FFBF (55% vs 50%, p = 0.012). No significant differences in DM cumulative incidence were found. Conclusions: For patients with GS ≥7 receiving SRT, clinicians should weigh FFBF benefits of WPRT and ADT against toxicities. Future studies should explore the impact of WPRT on quality of life, clinical progression, and overall survival. Patient summary: We evaluated patients with prostate cancer treated with radiation after surgery to remove the prostate. Both radiation to the pelvic lymph nodes and suppression of testosterone lowered the chance of increasing prostate-specific antigen (a marker for cancer returning). Among patients treated with postprostatectomy salvage radiation therapy for Gleason score 7–10 prostate cancer, this multi-institutional database found improved freedom from biochemical failure when whole pelvis radiation therapy or androgen deprivation therapy was added to prostate bed–only radiation therapy.