High-Intensity Focused Ultrasound (HIFU) for Prostate Cancer

High-intensity focused ultrasound (HIFU) is a minimally invasive, radiation-free treatment that uses precisely targeted acoustic energy to destroy prostate cancer tissue through the application of heat. The technology concentrates high-energy ultrasound waves to a focal point within the prostate gland, raising the tissue temperature rapidly to levels that cause irreversible tissue destruction at the target site, while leaving the surrounding tissue largely unaffected.

HIFU is delivered through a probe placed in the rectum (transrectal HIFU). The prostate gland lies just a few centimeters from the anterior rectal wall, making the transrectal approach highly effective for transmitting ultrasound energy to the prostate. Imaging guidance enables the treating physician to map the prostate and direct treatment precisely to tumor-bearing regions.

HIFU can be applied in two principal strategies:

• Whole-gland ablation: The entire prostate gland is treated, aiming for complete destruction of all prostatic tissue, including areas of cancer.
• Focal (hemi-gland or targeted) ablation: Only the portion of the prostate containing the tumor is treated, preserving the remainder of the gland and its surrounding functional structures. Focal HIFU has emerged as an organ-sparing strategy for carefully selected patients with localized, low-to-intermediate risk prostate cancer, offering the potential for meaningful preservation of urinary and sexual function compared with whole-gland treatments.

Patient selection and pre-procedural assessment

• Not all patients with prostate cancer are appropriate candidates for HIFU. Comprehensive pre-procedural evaluation includes:
  
  • Multi-parametric MRI of the prostate: MRI is essential for characterizing the location, volume, and extent of the cancer within the prostate gland. For focal HIFU, accurate tumor mapping on MRI is required to define the treatment zone.
  • Prostate biopsy: Histopathological confirmation of cancer grade and location is required. For focal ablation, biopsy of the contralateral prostate lobe (to confirm it is cancer-free) is essential.
  • Baseline functional assessment: Pre-procedural assessment of urinary function and sexual function is performed to document baseline status and facilitate meaningful post-treatment comparison.
  • Prostate size assessment: HIFU is most suitable for prostates that are not excessively large. Patients with large prostates may require a preliminary to reduce prostate volume and improve acoustic access before HIFU.
    
    

Patient preparation instructions

• Fasting from midnight the evening before the procedure.
• A bowel preparation (enema) is administered prior to the procedure to clear the rectum, reducing the risk of contamination.
• Medications are reviewed and adjusted as directed.
• The procedure is performed under general or spinal anesthesia; the anesthetic choice is discussed with the patient in advance.

Before the procedure begins

• After the patient is anesthetized and positioned, a transrectal ultrasound probe of the HIFU system is gently introduced into the rectum and positioned adjacent to the prostate. An intraoperative ultrasound image of the prostate is obtained and co-registered with the pre-procedural MRI to create a precise treatment map. 

During the procedure

• The HIFU system delivers precisely focused high-energy ultrasound pulses to predetermined coordinates within the prostate, following the mapped treatment plan. Each individual ablation pulse is brief, followed by an interval for imaging and repositioning. The focal point generates temperatures exceeding 80°C at the target site. By systematically moving the focal point through the treatment region, the entire target volume is ablated zone by zone.
• A rectal cooling device is used throughout the procedure to circulate cooled water between the transrectal probe and the rectal mucosa, protecting the rectum from thermal injury. A urethral catheter is inserted to drain the bladder during and after the procedure.
• The total duration of the HIFU procedure is typically 2–4 hours, depending on the volume of tissue being treated (whole-gland vs. focal ablation) and prostate size.

After the procedure

• HIFU is most commonly performed as a day-case (outpatient) or short-stay procedure. Most patients are discharged the same day or after one overnight stay. A urethral catheter remains in place for a specified period after the procedure (typically 1–2 weeks) to allow healing of the ablated tissue and to manage the transient voiding dysfunction that occurs as the necrotic tissue is expelled. Patients should expect some degree of urinary frequency, urgency, and discomfort during this period, which resolves progressively.

HIFU is associated with a favorable safety profile compared with radical prostatectomy and radiotherapy, particularly with respect to urinary continence and erectile function. However, as with all medical procedures, risks exist:

• Urinary retention and voiding difficulty: Swelling of the treated prostate tissue causes transient obstruction of the urethra in the early post-procedure period. Catheter drainage manages this until the sloughed tissue is expelled and voiding function is restored.
  
  
• Urinary tract infection: Infection related to catheterization can occur and is treated with antibiotics.
  
  
• Urethral stricture or bladder neck contracture: Scarring of the urethra at the site of treated tissue can cause progressive narrowing (stricture), requiring subsequent endoscopic treatment.
  
  
• Urinary incontinence: Stress urinary incontinence following HIFU is significantly less common than after radical prostatectomy, particularly with focal HIFU. 
  
  
• Erectile dysfunction: Focal HIFU is associated with substantially better preservation of erectile function than radical prostatectomy or whole-gland HIFU, because the neurovascular bundles on the untreated side are spared. 
  
  
• Recto-urethral fistula: A rare but serious complication in which an abnormal connection forms between the rectum and the urethra, allowing communication between the two passages. This is uncommon with modern HIFU systems equipped with rectal cooling.
  
  
• Incomplete ablation / local recurrence: HIFU may not achieve complete destruction of all cancer cells, particularly in areas at the periphery of the treatment zone or in patients with larger or multifocal cancers. Post-treatment surveillance with prostate-specific antigen (PSA) monitoring and biopsy identifies any residual or recurrent cancer.

Post-procedure monitoring

• After HIFU, PSA is measured at regular intervals to assess the completeness of tissue ablation and monitor for evidence of cancer persistence or recurrence. Following successful whole-gland HIFU ablation, PSA should fall significantly and remain at a low stable level. 

Follow-up biopsy

• A follow-up prostate biopsy is typically performed months after the procedure to confirm pathological cancer clearance within the treated zone, and to assess for any residual cancer that may require further treatment.

Treatment of residual or recurrent disease

• If follow-up evaluation reveals persistent or recurrent cancer, salvage treatment options may include:
  • Repeat HIFU ablation of the affected area
  • Radiation therapy (external beam or brachytherapy)
  • Radical prostatectomy
  • Systemic therapy for disease that is no longer organ-confined

Long-term surveillance

• Patients treated with HIFU for prostate cancer require long-term urological follow-up, including PSA monitoring at defined intervals, to detect any late recurrence and ensure ongoing cancer control.