Evidence shows HIFU can provide cancer control outcomes comparable to those associated with radical prostatectomy or radiation therapy in properly selected patients.
High-intensity focused ultrasound (HIFU) can be considered ready for prime time as a treatment for localized prostate cancer considering evidence that it can provide cancer control outcomes comparable to those associated with radical prostatectomy or radiation therapy. The suitability of HIFU as an alternative to traditional options for management of prostate cancer, however, depends on proper patient selection, said Cary N. Robertson, MD.
“HIFU is a bridge treatment that lies halfway between active surveillance and traditional definitive therapies, and it gives us another tool for meeting individual patient needs” said Dr. Robertson, associate professor of surgery (urology) at Duke University Medical Center, Durham, NC.
Dr. Robertson noted that per FDA guidance, the registration trial investigating the efficacy and safety of the Ablatherm-HIFU device only enrolled subjects with low-risk prostate cancer. When the application for approval was first reviewed, however, members of the FDA’s Gastroenterology-Urology Devices Panel expressed concern that the treatment benefit did not outweigh the risks in this population of men who may qualify for active surveillance as initial treatment. This may not apply to high-volume low-risk prostate cancers, however.
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“My main message about HIFU’s role for management of localized prostate cancer is that while it can be used to treat men with high-volume, low-risk disease, it is not meant for only that setting,” said Dr. Robertson.
According to Dr. Robertson, optimal candidates for HIFU are men with “low” intermediate-risk prostate cancer who have a small gland (<40 cc) that can be treated without the need for an adjuvant procedure to downsize or debulk the prostate.
“A patient with high-volume Gleason grade 3+3=6 or low-volume Gleason grade 7 (3+4) prostate cancer would be ideal, but HIFU may also be considered for a man with a small focus of higher grade disease,” he said.
One niche for whole-gland HIFU is for a subgroup of men who have comorbidities that make them poor candidates for surgery or radiation therapy. And, when prostate cancer is unilateral, HIFU hemiablation is something that can be considered as an alternative to surgery or radiation therapy by men who are concerned about the functional side effects of those traditional interventions.
“Hemiablation in men with unilateral prostate cancer is probably the future for HIFU because it has a favorable safety profile relative to traditional treatments for prostate cancer. In addition, available data indicate that hemiablation HIFU is associated with acceptable cancer control rates, although follow-up duration in studies of hemiablation HIFU is much shorter,” Dr. Robertson said.
Next: HIFU outcomes
Currently, the largest amount of published data on HIFU outcomes is reported out of centers in France, Germany, and the United Kingdom and pertains to whole-gland treatment. These results show good efficacy using HIFU to treat localized prostate cancer, said Dr. Robertson.
He cited long-term data from a HIFU center of excellence in Munich. Chaussy and Thüroff reported outcomes for 704 patients with a mean follow-up of 5.3 years (range, 1.3 to 14 years); 78.5% of men in the series had intermediate- or high-risk disease.1 Cancer-specific survival was 99%, metastasis-free survival was 95%, and 10-year salvage treatment-free rates were 98% in low-risk, 72% in intermediate-risk, and 68% in high-risk patients. The investigators reported that PSA nadir and Gleason score predicted biochemical failure, side effects were moderate, and the HIFU retreatment rate since 2005 was 15%.
“It is important to realize that after HIFU, there may be a small residual amount of tumor as documented by biopsy or MRI and biopsy. But, HIFU is repeatable, and including patients who had a second treatment, long-term cancer control rates measured by freedom from biochemical recurrence are similar for HIFU as for surgery and radiation therapy across the spectrum from low-risk to high-risk disease,” Dr. Robertson said.
Dr. Robertson noted findings from analyses of data collected in the IDE registration trial for the Ablatherm platform showing that at 2 years post-HIFU, of the 28% of men demonstrating a positive biopsy after a single HIFU treatment, the per core negative biopsy rate was significantly increased compared with baseline.2
Cancer control outcomes for HIFU hemiablation are encouraging, but the data are less mature. French investigators published on a series of 111 patients prospectively followed after HIFU hemiablation and reported a radical treatment-free survival rate of 89% at 2 years.3
Data from the French study of hemiablation HIFU support a benefit of the technique for minimizing morbidity with prostate cancer treatment. At 12 months after HIFU, continence was preserved in 97% of men and erectile function in 78%.
Safety data from studies of whole-gland HIFU show that loss of erectile function occurs at a rate of about 50%.4 While erectile function may be temporary, there is a protracted course until recovery, similar to radical prostatectomy, Dr. Robertson said.
The incidence of incontinence after whole-gland HIFU is 2% to 5%, and to avoid post-HIFU bladder outlet obstruction, it is recommended that men undergo a TURP procedure before or at the time of HIFU.4 In addition, urinary obstruction secondary to urethral stricture has been reported in 2% to 5% of men having whole-gland HIFU.4
Disclosure: Dr. Robertson is a consultant for EDAP TMS, Inc.
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1. Thüroff S, Chaussy C. Evolution and outcomes of 3 MHz high intensity focused ultrasound therapy for localized prostate cancer during 15 years. J Urol 2013; 190:702-10.
2. Robertson C, Sliwinski A, Wallen E, et al. Efficacy of high intensity focused ultrasound (HIFU) as a primary monotherapy for low risk localized prostate cancer: outcomes from the ENLIGHT Trial. J Urol 2016; 195(4 suppl):e198–9.
3. Rischmann P, Gelet A, Riche B, et al. Focal high intensity focused ultrasound of unilateral localized prostate cancer: a prospective multicentric hemiablation study of 111 patients. Eur Urol 2017; 71:267-73.
4. Crouzet S, Chapelon JY, Rouvière O, et al. Whole-gland ablation of localized prostate cancer with high-intensity focused ultrasound: oncologic outcomes and morbidity in 1002 patients. Eur Urol 2014; 65:907-14.
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