What is HIFU for Prostate Cancer and What are the Indications?
HIFU (High-Intensity Focused Ultrasound) is a thermal ablation technology that heats prostate tissue to 85°C to destroy cancer cells, but it should only be offered within clinical trials for localized prostate cancer due to lack of comparative effectiveness data and variable oncologic outcomes. 1
Technology Overview
HIFU is a minimally invasive treatment modality that uses focused ultrasound energy to achieve thermal ablation of prostate tissue, typically delivered transrectally. 2, 3 The technology creates focal temperatures reaching 85°C, resulting in coagulative necrosis of targeted tissue. 2
Current Guideline Recommendations
Primary Treatment Context
The AUA/ASTRO/SUO guidelines explicitly state that HIFU should only be offered as an alternative treatment modality for localized prostate cancer within the context of a clinical trial. 1 This recommendation stems from:
- Absence of prospective randomized or comparative effectiveness data versus traditional treatments 1
- Variable published 5-year oncologic outcomes attributable to lack of consensus on objective response criteria 1
- No agreement on defining the ideal patient for focal therapy 1
Risk-Stratified Recommendations
For high-risk localized prostate cancer (T3b-T4, Gleason 8-10), HIFU is explicitly NOT recommended outside clinical trials. 1 The AUA guidelines note that HIFU performs poorly as monotherapy in this population, with only 47% success rates. 4
For low and intermediate-risk disease, HIFU may be considered only within clinical trial settings, with the understanding that intermediate-risk patients often require multiple sessions or adjuvant treatments (77% success rate after single session). 4, 5
Salvage Therapy Setting
For local recurrence after radiation therapy or radical prostatectomy, HIFU salvage therapy achieves 5-year biochemical recurrence-free survival rates of 50-60%. 4, 6, 7 However, the European Urology guidelines recommend that HIFU should not be considered first-line for recurrent disease, as it has inferior oncological outcomes compared to salvage SBRT, HDR brachytherapy, or radical salvage prostatectomy. 6
Clinical Outcomes Data
Efficacy by Risk Group
Research data demonstrates variable success rates:
- Low-risk patients: 84-100% biochemical success rates (PSA <0.5 ng/mL) 2, 5
- Intermediate-risk patients: 77-86% success rates 2, 5
- High-risk patients: Only 43-47% success rates 2, 5
Negative biopsy rates at 6 months post-treatment range from 93.4% in low/intermediate-risk to 63.1% in high-risk patients. 2
Salvage HIFU Outcomes
For radiation recurrence, salvage HIFU shows 5-year biochemical disease-free survival of 52% overall, with risk-stratified rates of 100% (low-risk), 86% (intermediate-risk), and only 14% (high-risk). 7
Complications and Quality of Life
Tumor location influences oncologic outcomes with HIFU. 1 Common complications include:
- Urethral stricture: ~18-32% requiring transurethral procedures 2, 3
- Erectile dysfunction: 61% of patients 6
- Grade I urinary incontinence: ~18% 7
- Rectourethral fistula: Rare but serious, particularly in post-radiation patients 7, 3
Critical Pitfalls to Avoid
Never perform HIFU based solely on positive PET-PSMA imaging due to 8% false-positive rates from post-treatment changes. 4, 6 Histological confirmation is mandatory before any ablative therapy. 6
Do not use the Phoenix criterion (nadir + 2 ng/mL) to define HIFU failure, as this was validated for radiation therapy, not ablation. 4, 6
Avoid combining biopsy and focal ablation simultaneously - histological confirmation must always precede treatment. 4, 6
Prior TURP defects represent a relative contraindication due to increased risk of urethral complications. 1
Pre-Treatment Requirements for Salvage HIFU
When considering salvage HIFU, mandatory evaluation includes:
- Histological confirmation of recurrence via systematic and targeted biopsy 6
- PET-PSMA and multiparametric MRI for staging 6
- Life expectancy >5-10 years 6
- Recurrence should be Grade Group ≥2 6
- Prior radiation toxicity should be minimal or resolved 6
Alternative Standard Treatments
Radical prostatectomy and radiotherapy plus ADT remain the standard treatment options for localized prostate cancer with proven mortality benefits. 1 For salvage situations, SBRT or HDR brachytherapy are preferred over HIFU due to favorable toxicity profiles and equivalent oncological efficacy. 6