Salvage Brachytherapy in Prostate Cancer after Radiation Failure: HDR vs LDR

Abstract

To evaluate efficacy and toxicity of HDR and LDR brachytherapy (BT) as salvage modalities in prostate cancer (PCa) patients after primary radiotherapy failure. Between 2001 and 2016, 126 patients were treated with BT as salvage local treatment, 47 with LDR and 79 with HDR. All patients had biopsy proven local relapse. A total of 31 patients (25%) received androgen deprivation therapy at the time of BT. Post-salvage BT progression and cause-specific-mortality of both treatment modalities (LDR and HDR) were analyzed. Toxicity was evaluated by RTOG scale. Median follow-up was 52 months (4-186) from BT. In 23 patients, HDR was used as a salvage modality because LDR-BT was already used as initial treatment. A total of 39 patients progressed after salvage BT, 15 (32%) in LDR and 24 (30%) in HDR group. The 5-yr cause-specific survival was 97% with LDR and 94% with HDR (p=ns). On multivariate analysis, factors associated to progression were initial score Gleason ≥7 (p=0.02), time to BF from initial RT < 30 months (p=0.00) and nadir PSA post-salvage BT (p=0.00). A total of 14 patients had urethral stenosis, 18 urinary incontinence and 13 haematuria. Grade ≥3 toxicity was observed in 22%. Salvage BT in PCa patients who have local failure after radiation therapy can achieve local control > 70% with an adequate toxicity profile. There were not significant differences observed neither in efficacy nor in toxicity between HDR and LDR modalities.