Salvage high-intensity focused ultrasound for locally recurrent prostate cancer after low-dose-rate brachytherapy: oncological and functional outcomes

Objectives: To evaluate the oncological and functional outcomes of salvage high-intensity focused ultrasound (S-HIFU) for locally recurrent prostate cancer after low-dose-rate (LDR) brachytherapy.

Patients and methods: Clinical phase II studies (2003-2015) included 50 consecutive patients with post-brachytherapy local recurrence treated by S-HIFU. S-HIFU was performed with post-external beam radiotherapy (EBRT) parameters and, since 2008, with specific post-brachytherapy parameters. Treatments were whole-gland ablation and, since 2009, hemi-ablation in cases of unilateral prostate cancer. The primary objective was to assess oncological outcomes: treatment failure-free survival, progression-free survival (PFS), overall survival (OS), cancer-specific survival (CSS), and metastasis-free survival (MFS) rates. The secondary objective was to evaluate adverse events, continence, and erectile function. Kaplan-Meier analysis estimated oncological outcomes.

Results: In all, 13 patients were treated with post-EBRT parameters, 37 with post-brachytherapy parameters, 35 with whole-gland treatment, and 15 with hemi-ablation. The median follow-up was 4.6 years. After S-HIFU, the median prostate-specific antigen level was 0.3 ng/mL. At 6 years, treatment failure-free survival, PFS, OS, CSS, and MFS rates were 41%, 45%, 93%, 98%, and 80%, respectively. Post-brachytherapy compared with post-EBRT parameters reduced Grade 2-3 incontinence (34% vs 62%, P = 0.015). Incontinence, bladder outlet obstruction and Grade ≥III complications were significantly reduced with hemi-ablation compared with whole-gland treatment (14% vs 54%, P < 0.001; 13% vs 46%, P = 0.03; 13% vs 63%, P = 0.001; respectively). Before S-HIFU, 25 patients had a five-item version of the International Index of Erectile Function score of ≥17, which was maintained in 48% at 12 months.

Conclusion: S-HIFU for locally recurrent prostate cancer after LDR brachytherapy is associated with favourable survival rates at a price of significant morbidity. Dedicated post-brachytherapy parameters and hemi-ablation improve the safety of the treatment.