Focal Salvage HIFU in radiorecurrent prostate cancer

OBJECTIVE: To assess short to medium term cancer control rates and side effects of focal salvage High Intensity Focused Ultrasound (HIFU). MATERIALS AND METHODS: A retrospective registry analysis identified 150 men who underwent focal salvage HIFU (Sonablate 500) (November 2006-August 2015). Metastatic disease was excluded using the nodal assessment on the pelvic MRI, a radioisotope bone scan and PET imaging (choline-FDG-PET or Choline PET-CT). In our current clinical practice, metastatic disease must be ruled out by both Choline PET and bone scan. Localisation of cancer was by multi-parametric prostate MRI (T2W, diffusion-weighting, dynamic contrast enhancement) with systematic or template prostate mapping biopsies. Primary outcome was a composite failure incorporating biochemical failure (BF) and/or positive localised or distant imaging and/or positive biopsy and/or systemic therapy and/or metastases/prostate cancer specific death. Secondary outcome was BF using the Phoenix-ASTRO definition (nadir+2ng/ml). We used Kaplan-Meier analysis and Cox-proportional hazards regression to quantify the effect of the determinants on the endpoints. RESULTS: Mean age at focal salvage therapy was 69.8 years (SD 6.1) and median PSA pre-focal salvage treatment was 5.5 ng/ml [IQR 3.6-7.9). Median follow-up was 35 months (IQR 22-52). Patients were classified as low 2.7% (4/150), intermediate 39.3% (59/150) and high-risk disease 41.3% (62/150) according to D'Amico classification, prior to focal salvage HIFU. Composite failure occurred in 61% (91/150) and BF occurred in 51.3% (77/150). The Kaplan-Meier composite endpoint free survival (CEFS) at 3 years was 40% (95% CI 31-50) for the entire group. Kaplan-Meier estimates of CEFS were 100%, 49% and 24% at 3 years in low, intermediate and high D'Amico risk groups pre-salvage, respectively. The Kaplan-Meier biochemical disease free survival (BDFS) at 3 years was 48% (95% CI 39-59) for the entire group. Kaplan-Meier estimates of BDFS was 100%, 61% and 32% at 3 years in low, intermediate and high D'Amico risk groups pre-salvage, respectively. Complications included urine infection (11.3%; 17/150), bladder neck stricture (8%; 12/150), recto-urethral fistula after 1 HIFU procedure (2%; 3/150) and osteitis pubis (0.7%; 1/150). CONCLUSION: Focal salvage HIFU confers a relatively low complication and side-effect rate. Composite endpoint free survival and biochemical control in the short to medium term is reasonable, especially in this relatively high risk cohort but still on the lower end compared to current whole gland salvage therapies. Focal salvage therapy may offer disease control in high risk men whilst minimising additional treatment morbidities. This article is protected by copyright. All rights reserved.