Targeted Ultrasound Therapy for Prostate Cancer: A 2-Year Study on Safety and Effectiveness

Table of Contents

• Introduction: Why This Research Matters
• Who Was Studied and How?
• The Treatment: How MRI-Guided Focal HIFU Works
• Key Findings: Cancer Control and Treatment Failure
• Side Effects and Safety
• PSA Level Results
• Quality of Life and Functional Outcomes
• Understanding the Study's Limitations
• What This Means for Patients
• Source Information

Introduction: Why This Research Matters

Prostate cancer is one of the most common cancers in men. For decades, the standard curative treatments have been radical prostatectomy (surgical removal of the entire prostate) or radiotherapy (radiation to the whole prostate). While these are effective, they often come with significant side effects, including long-term difficulties with urination, urinary incontinence (leakage), and erectile dysfunction.

This has led to a search for treatments that can cure the cancer while better preserving the organ and a man's quality of life. Focal therapy is one such approach. Instead of treating the entire prostate, focal therapy aims to destroy only the area containing the significant tumor, leaving the healthy surrounding tissue untouched.

High-Intensity Focused Ultrasound (HIFU) is a leading focal therapy technology. It uses a precisely aimed beam of ultrasound energy to heat and destroy cancer cells in a specific spot. This study was designed to see how feasible, safe, and effective MRI-guided focal HIFU is for men with low- and intermediate-risk prostate cancer over a two-year period.

Who Was Studied and How?

This was a prospective study, meaning patients were enrolled and followed forward in time according to a specific plan. It was conducted at three hospitals in Austria from 2021 to 2024. Importantly, this was a single-arm, feasibility trial. This means all participants received the HIFU treatment, and there was no comparison group receiving surgery or radiation. The main goals were to check if the treatment was practical to perform and to monitor early results on cancer control and side effects.

The study included 52 men, but one was excluded because his PSA level was too high at the start, leaving 51 men in the final analysis. To be eligible, patients had to have:

• Newly diagnosed, non-metastatic prostate cancer.
• Low- or intermediate-risk disease (using the D'Amico classification system).
• A PSA level at or below 15 ng/mL.
• A tumor stage of T2b or less (meaning the cancer was confined to the prostate).
• An MRI scan showing a suspicious lesion that was confirmed by a targeted biopsy.
• No significant cancer suspected on the opposite side of the prostate.

All patients were fully informed about standard options (surgery, radiation, active surveillance) and chose not to pursue active surveillance. The median age of participants was 67 years, and the median PSA level before treatment was 7.55 ng/mL.

The Treatment: How MRI-Guided Focal HIFU Works

The treatment used a device called the Focal One system. Before the procedure, doctors used MRI scans to precisely map the prostate and the tumor location. This planning was done in collaboration between urologists and radiologists.

During the treatment, which was done under general anesthesia:

1. A probe was inserted into the rectum.
2. Using live ultrasound for guidance, the HIFU energy was focused only on the biopsy-confirmed tumor area. A safety margin of 9 mm (about a third of an inch) of tissue around the tumor was also treated.
3. In some cases, a contrast agent was used during the procedure to check if the ablation was complete; if any area looked untreated, an extra pass of HIFU was applied.
4. The procedure had a median time of 85 minutes, and the median volume of prostate tissue treated was 12 mL.
5. A Foley catheter (urinary catheter) was placed at the end and typically remained for a median of 5 days.

The neurovascular bundles (critical for erectile function) and the urethra were not specifically spared during this treatment, as the priority was completely treating the targeted area.

Key Findings: Cancer Control and Treatment Failure

The researchers tracked a primary outcome called Failure-Free Survival (FFS). This was defined as being free from needing salvage whole-gland therapy (surgery or radiation), systemic therapy, developing metastases, or dying from prostate cancer.

At the 24-month mark, the Failure-Free Survival rate was 94.1%. This means that 48 out of the 51 men (94.1%) did not require radical salvage treatment within two years. Only 3 patients (5.9%) needed salvage radiotherapy.

A crucial measure of success is whether cancer is still present after treatment. The protocol recommended a follow-up biopsy at 12 months.

• 31 out of 51 patients (60.1%) underwent at least one biopsy after HIFU.
• Of these 31 men, 26 had no detectable cancer on their biopsy, a success rate of 83.9%.
• Cancer was found in 5 men: three had low-grade (ISUP 1) cancer, one had intermediate-grade (ISUP 2), and one had high-grade (ISUP 4) cancer.

The three men who needed salvage treatment had different situations: one developed a high-grade cancer on the opposite side of the prostate, one had a low-grade cancer on the opposite side but his PSA kept rising, and one had intermediate-grade cancer in the original treatment area. No patients developed metastases or died from prostate cancer during the study.

Side Effects and Safety

The safety profile was closely monitored. A total of 14 patients (27%) experienced at least one adverse event related to the treatment.

The most common issue was transient acute urinary retention (inability to urinate), which occurred in 11 men (21.6%). This was typically managed with a catheter for a short period.

• 5 men (10%) needed a standard transurethral catheter.
• 6 men (12%) required a suprapubic catheter (placed through the abdomen into the bladder) under local anesthesia.
• 2 men (4%) later needed a procedure called a TURP (transurethral resection of the prostate) to relieve obstruction.

Other side effects included:

• Urinary tract infections in 3 patients (6%).
• Epididymitis (inflammation of a structure near the testicle) in 2 patients (4%).
• Only one new case of Grade 2 urinary incontinence (leakage during physical activity) was reported, and this was linked to a complicated infection in a patient with diabetes.

Importantly, there were no severe (Clavien-Dindo Grade 4 or 5) complications directly related to the HIFU procedure. Two patients died during follow-up from unrelated cardiovascular events (a heart attack and a heart valve rupture). One patient was diagnosed with bladder cancer 19 months after HIFU, but doctors considered this unlikely to be caused by the treatment.

PSA Level Results

PSA (Prostate-Specific Antigen) levels are tracked after prostate cancer treatment to monitor for recurrence.

In this study, PSA levels dropped sharply immediately after treatment:

• Baseline mean PSA: 7.55 ng/mL
• At 3 months post-HIFU: 2.31 ng/mL

This represents a 69.3% reduction in PSA levels. After this initial drop, PSA levels stabilized and remained in a low range for the rest of the study. At 24 months, the mean PSA was 2.7 ng/mL. This pattern of a sharp decline and then stabilization is a positive sign that the treated cancer cells were effectively destroyed.

The PSA response was consistent across patients with different initial cancer grades (ISUP 1, 2, and 3), with all groups maintaining low PSA levels over two years.

Quality of Life and Functional Outcomes

Preserving quality of life is a major goal of focal therapy. This study measured several key areas:

Urinary Symptoms (IPSS): The International Prostate Symptom Score measures urinary difficulties. Interestingly, outcomes depended on a patient's symptoms before treatment.

• Men who started with good urinary function maintained it throughout the two years.
• Men who started with moderate to severe symptoms saw significant improvement. Their average symptom score improved by 7.8 points (a 59% reduction) by 24 months, meaning their bothersome urination problems got much better.

Erectile Function (IIEF-5): Erectile function, measured by a questionnaire, showed a predictable pattern.

• Scores dropped slightly at the 3-month checkup (mean 14.9 vs. baseline 18.2).
• However, they largely recovered by 6-12 months and had returned to near-baseline levels by 24 months (mean 18.8). This indicates that any impact on erectile function was mostly temporary.

Overall Quality of Life (SF-36): Patients completed a comprehensive quality-of-life survey. Scores across all domains—including physical function, mental health, and pain—remained stable from baseline through the 12- and 24-month checkups. This is a strong indicator that the treatment did not negatively impact patients' overall well-being.

Understanding the Study's Limitations

While the results are encouraging, it's important to understand the study's limitations, as the authors openly acknowledge:

1. Short Follow-up: Two years is too short to know about long-term cancer control or very late side effects. Some cancers can recur many years later.
2. No Comparison Group: Because everyone got HIFU, we can't directly say it's better or as good as surgery or radiation. Larger trials comparing these treatments head-to-head are needed.
3. Small Number of Patients: With 51 patients, the study gives a good early signal but isn't large enough to provide definitive proof of effectiveness.
4. Not Everyone Had a Biopsy: Only 31 of the 51 men (61%) had the recommended 12-month biopsy. This means some cases of residual cancer might have been missed, potentially making the success rate look slightly better than it is.
5. COVID-19 Impact: The pandemic caused some scheduling delays, meaning some tests weren't done exactly on the planned dates.
6. Imperfect MRI: MRI scans are very good but not perfect at finding all prostate cancer. Some "MRI-invisible" cancers might have been missed before treatment or during follow-up.

What This Means for Patients

This study adds promising data to the growing evidence for focal HIFU as a treatment option for select men with localized prostate cancer. For patients, the key takeaways are:

• Focal HIFU appears to be a feasible and safe treatment that can effectively target the cancer area in the short term, with 94.1% of men avoiding more radical treatment for at least two years.
• Side effects are mostly mild and temporary. The most common issue, temporary urinary retention, is manageable. Significant long-term incontinence was rare (one case in this study), and erectile function showed good recovery.
• Quality of life is preserved. Patients did not see a decline in their overall health-related quality of life, and many with urinary symptoms actually saw improvement.
• Patient selection is critical. This treatment is currently best suited for men with low- or intermediate-risk cancer that is clearly visible on MRI and confirmed by biopsy, with no signs of significant cancer elsewhere in the prostate.

The authors conclude that these positive early results support moving forward with larger, randomized controlled trials that compare focal HIFU directly to standard whole-gland treatments over a longer period (5-10 years). For now, as noted in guidelines, focal therapy like HIFU should ideally be performed within clinical trials or well-regulated settings where outcomes are carefully tracked.

Source Information

Original Article Title: "Focal Therapy Using High-Intensity Focused Ultrasound for Low- and Intermediate-Risk Prostate Cancer: Results from a Prospective, Multicenter Feasibility Trial"
Authors: Gabor Rosta, Simon Turba, Dong-Ho Mun, Azad Shehab, Leon Saciri, Paul F. Engelhardt, Patricia Weisz, Claus Riedl, Ghazal Ameli, Stephan Doblhammer, and Harun Fajkovic
Published in: Cancers 2025, 17, 3429.
Note: This patient-friendly article is based on peer-reviewed research and aims to accurately translate the study's findings, methods, and conclusions for an educated patient audience.