Recommending either whole-gland or focal HIFU cannot be justified when their pros and cons are judged relative to the appropriate comparator.
Addressing the question of whether high-intensity focused ultrasound (HIFU) for localized prostate cancer is ready for prime time requires a multi-part discussion that considers the whole-gland approach separately from hemiablation/focal HIFU, says Erik P. Castle, MD.
He concluded, however, that there is no justification for recommending either modality when its potential pros and cons are judged relative to those of the appropriate comparator.
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Dr. Castle is professor of urology at Mayo Clinic, Phoenix. Discussing the role of HIFU for localized prostate cancer, he said that whole-gland HIFU would be considered as a treatment for patients whose cancer is expected to impact their survival and should be compared against radical prostatectomy. On the other hand, hemiablation/focal HIFU aims to address concern about overtreatment of low-risk prostate cancer and should be considered in relation to active surveillance.
Taking into account data on cancer control and complications, Dr. Castle said that whole-gland HIFU has yet to be proven equal to standard therapies as far as intermediate- and long-term outcomes. He foresaw potential growth of hemiablation/focal HIFU, but concluded that active surveillance is the better option for men with low-risk disease seeking to preserve quality of life.
“There is no free lunch with prostate cancer therapy. Patients pay upfront with continence and potency issues if they choose radical prostatectomy. If they choose whole-gland HIFU, they pay later in life with the possible need for retreatment and other issues, such as stricture,” Dr. Castle explained.
“Whereas hemiablation/focal HIFU might be considered for a patient who is a candidate for active surveillance because he has low-risk disease, determining when these men should be treated is the real target for their care, and I think we are doing a better job with that now than we were a decade ago.”
Next: Whole-gland HIFU
Dr. Castle said that because whole-gland HIFU is intended to be an extirpative procedure, it should be compared against radical prostatectomy. Therefore, it is inappropriate to evaluate the success of whole-gland HIFU using radiation criteria. More relevant are reports showing that whole-gland HIFU left vital tissue at ventral, lateral, and dorsal aspects of the prostate and residual cancer in a significant proportion of patients.1–3
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Complication rates after whole-gland HIFU were also high. Impotence occurred in up to 70% of men, and prolonged retention, stress urinary incontinence, and urethral/prostate stricture were reported at rates in the range of 22% to 30%.4,5
Dr. Castle acknowledged that those data are from earlier patient series and that results are improved considering more recent studies of whole-gland HIFU. The outcomes, however, are not good enough to support its use over radical prostatectomy, he said.
Dr. Castle cited a study reported by Ganzer et al that included more than 500 patients with up to 14 years of follow-up.6 Using Phoenix criteria, the analyses showed biochemical disease-free survival rates of 81% at 5 years and 61% at 10 years. Overall, 75 patients (13.9%) died and 18 patients (3.3%) died of prostate cancer. The salvage treatment rate was 18%, and the rate of bladder outlet obstruction was almost 30%.
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Dr. Castle also noted that whole-gland HIFU is restricted to men with a low prostate volume (<40 cc). Because of that limitation, up to 50% of men have had a neoadjuvant procedure (ie, androgen deprivation to shrink the gland or debulking with transurethral resection of the prostate) that introduces additional risks. In addition, because of the risk for urinary retention, it is often recommended that a bladder outlet procedure be performed with whole-gland HIFU.
Next: Hemiablation/focal HIFU
Reported outcomes for hemiablation/focal HIFU show that complication rates are lower than for whole-gland HIFU.7,8 However, problems with potency, incontinence, and urinary retention still exist, and the rate of retreatment is higher compared with whole-gland HIFU.
“Advocates for hemiablation/focal HIFU say that the ability to retreat is one of its advantages, but as a bottom line, I would argue that there are no treatment-related side effects associated with active surveillance,” Dr. Castle said.
He acknowledged that men choosing active surveillance will be having biopsies, which also exposes them to potential side effects. In addition, the knowledge that they have untreated cancer can create a psychological burden for some men on active surveillance.
“In my mind, however, the bottom line is that you either treat cancer or you don’t,” Dr. Castle said. “Hemiablation/focal HIFU may be positioned as a compromise that hopefully causes fewer side effects than other interventions and provides some reassurance for patients who think they would feel better having some treatment. But I think we need to do a better job giving patients realistic expectations based on our learning that we don’t need to treat everybody.”
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1. Van Leenders GJ, Beerlage HP, Ruijter ET, et al. Histopathological changes associated with high intensity focused ultrasound (HIFU) treatment for localised adenocarcinoma of the prostate. J Clin Pathol 2000; 53:391-4.
2. Beerlage HP, van Leenders GJ, Oosterhof GO, et al. High-intensity focused ultrasound (HIFU) followed after one to two weeks by radical retropubic prostatectomy: results of a prospective study. Prostate 1999; 39:41-6.
3. Uchida T, Illing RO, Cathcart PJ, et al. To what extent does the prostate-specific antigen nadir predict subsequent treatment failure after transrectal high-intensity focused ultrasound therapy for presumed localized adenocarcinoma of the prostate? BJU Int 2006; 98:537-9.
4. Rebillard X, Gelet A, Davin JL, et al. Transrectal high-intensity focused ultrasound in the treatment of localized prostate cancer. J Endourol 2005; 19:693-701.
5. Gardner TA, Koch MO. Prostate cancer therapy with high-intensity focused ultrasound. Clin Genitourin Cancer 2005; 4:187-92.
6. Ganzer R, Fritsche HM, Brandtner A, et al. Fourteen-year oncological and functional outcomes of high-intensity focused ultrasound in localized prostate cancer. BJU Int 2013; 112:322-9.
7. Ganzer R, Hadaschik B, Pahernik S, et al. Prospective multicenter phase II study on focal therapy (hemiablation) of the prostate with high intensity focused ultrasound. J Urol 2017 Oct 26 [Epub ahead of print].
8. van Velthoven R, Aoun F, Marcelis Q, et al. A prospective clinical trial of HIFU hemiablation for clinically localized prostate cancer. Prostate Cancer Prostatic Dis 2016; 19:79-83.
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