New Noninvasive Technique for Prostate Cancer Ablation

By David A. Levy, MD

A minimally invasive ablative technique called high-intensity focused ultrasound (HIFU) is a recently FDA-approved alternative to radiation or surgery for certain men with prostate cancer. For those who are eligible for the procedure, HIFU offers outcomes essentially equivalent to radiation, but with potentially fewer side effects.

HIFU waves energize localized tissues to about 80 degrees Celsius and cause a lethal tissue pressure drop of 20,000-30,000 bars, resulting in coagulative necrosis and tumor death. The new technique does so with robotic precision, offering a focal beam width of 1.7 mm, which helps minimize damage to healthy tissue and improve overall quality of life after treatment.1,2 The procedure relies on a computer-driven robotic-assisted technique, carried out under general anesthesia and delivered through a transrectal ultrasound probe. There are no incisions and no need for pain medication after treatment.

Figure 1a. (schematic) Tissue impact footprint is 1.7 mm diameter x 24 mm maximum length. Figure 1b. (photomicrograph) The zone of coagulative necrosis (right) is clearly distinct from adjacent tissue not impacted. Robotic control advances the probe at 1.7 mm intervals under the surgeon’s direction.

Advantages of HIFU

Throughout the procedure, the prostate gland is repeatedly imaged using a combination of real-time ultrasound and static multiparametric magnetic resonance imaging (mp-MRI). This provides surgeons with detailed information on tumor size and location, helping maximize disease ablation and sparing healthy surrounding tissue.

Furthermore, sensitive structures around the gland, including urinary sphincter, rectal wall and neurovascular bundles, are protected. Occurrence of common ailments of surgical and radiological treatments, including incontinence, impotence and rectal fistula, therefore, remain very low.

HIFU research

In 2010, Crouzet et al reported outcomes on 803 patients treated at six French centers. The five- and seven-year biochemical disease-free survival (DFS) for low-risk patients was 83 and 75 percent, respectively. For intermediate-risk patients, five- and seven-year DFS was 72 and 63 percent (Phoenix criteria), respectively.3

In 2013, Blana et al, reported on 538 patients with maximum follow up of 14 years. The 10 year cancer specific survival rate was 96.7 percent, with 10-year metastasis-free survival of 99.6 percent, 94.3 percent and 84.6 percent for low, intermediate and high-risk patients, respectively.4

In 2014, the Crouzet team published a comprehensive follow-up report on 1,002 HIFU-treated patients. They reported a median nadir PSA of 0.14 ng/ml. The eight-year biochemical DFS rates (Phoenix definition, nadir + 2) for low, intermediate and high risk patients were, 76%, 63% and 57%, respectively, (P= < 0.001). Procedure-related morbidity was limited to incontinence (3.1%) and bladder outlet obstruction, (5.9%).5 Based on the peer reviewed published data, careful patient selection is anticipated to yield excellent disease control with a low risk of procedure related morbidity.

Favorable post-treatment results

Prostate cancer continues to be a major issue for American men with more than 161,360 new cases per year and 26,730 deaths attributed to the disease. Despite continued efforts to reduce treatment-related morbidities, urinary incontinence and impotence remain major hurdles in delivering curative treatment.

Compared with studies of other ablative techniques, data indicate that HIFU offers favorable post-treatment biopsy results. Overall outcomes for HIFU are encouraging and this new technology is associated with low procedure-related morbidity. Based on positive published reports, Cleveland Clinic now offers HIFU at Cleveland Clinic Euclid Hospital’s outpatient surgery center, becoming the first in our region to do so.

Dr. Levy is a urologist on staff at Cleveland Clinic’s Glickman Urological & Kidney Institute.

References

1. Chaussy C, Thueroff S, Rebillard X, et al. Technology insight: high-intensity focused ultrasound for urologic cancers. Nat Clin Pract Urol. 2005;2(4):191-8.
2. Cahussy C, Thueroff The use of high-intensity focused ultrasound in prostate cancer. In: Ukimura O, Gill IS, eds, Contemporary Interventional Ultrasonography. In: Urology. London:Springer; 2009:63-73.
3. Crouzet S, Rebillard X, Chevallier D, et al. Multicentric oncologic outcomes of high-intensity focused ultrasound for localized prostate cancer in 803 patients. Eur Urol. 2010;58:559-66.
4. Ganzer R, Fritsche HM, Brandtner A, et al. Fourteen-year oncological and functional outcomes in high-intensity focused ultrasound in localized prostate cancer. BJU Int. 2013 Aug;112(3):322-9. doi: 10.1111/j.1464-410X.2012.11715.x. Epub 2013 Jan 28.
5. Crouzet S, Chapelon JY, Rouviere O, et al. Whole-gland ablation of localized prostate cancer with high-intensity focused ultrasound: oncologic outcomes and morbidity in 1,002 patients. Eur Urol. 2014 May;65(5):907-14.