High-intensity focused ultrasound shows acceptable recurrence-free rate in prostate cancer

September 1, 2009

A single session of high-intensity focused ultrasound as primary therapy for localized prostate cancer results in an acceptable rate of biochemical-free recurrence.

Chicago-A single session of high-intensity focused ultrasound (HIFU) as primary therapy for localized prostate cancer results in an acceptable rate of biochemical-free recurrence, according to prospective data from a single-institution study presented at the AUA annual meeting.

In the study, at a median follow-up of 12 months, 70% of patients were free of biochemical recurrence according to a post-radical prostatectomy definition, while 96% of patients were free of biochemical recurrence according to a post-radiation therapy definition, said Jehonathan Pinthus, MD, professor of urology/surgical oncology at McMaster University, Hamilton, Ontario.

"We looked at prostate-specific antigen response using the same criteria used following radical prostatectomy, and we showed that the results are very encouraging in patients with low- and intermediate-risk disease," Dr. Pinthus told Urology Times.

Treatment was performed using the Ablatherm Integrated Imaging Model system (EDAP TMS, Vaulx en Velin, France), a third-generation HIFU system, without peri-HIFU transurethral resection of the prostate.

"This system has very sophisticated integrated imaging in real time, so we can refine the effect," said Dr. Pinthus.

A probe delivers HIFU energy to prostatic tissue transrectally. The procedure takes about 2 hours and is performed on an outpatient basis under spinal anesthesia.

'Encouraging' PSA nadir

Biochemical recurrence was assessed according to three definitions: Stephenson (PSA >0.4 ng/mL followed by an increase), Horwitz (two consecutive rises of at least 0.5 ng/mL), and Phoenix (PSA nadir +2.0 ng/mL "at call"). PSA levels were assessed every 3 months.

After a median follow-up of 12 months, mean and median absolute PSA nadir levels were 0.28 and 0.06 ng/mL, respectively, achieved in a median of 3 months, and remained unchanged in 70% of the patients throughout the follow-up.

Pre-HIFU PSA and post-HIFU PSA nadir levels predicted biochemical failure. "Biochemical failure usually occurs in the first year and plateaus thereafter," said Dr. Pinthus.

"As urologists, we try to treat patients with the least damage. The question now is, are we overtreating patients?" he said. "I think that HIFU is better than cryotherapy in terms of the side effect profile and the biological results. It's not an operation. The major side effect is that the patient has to be with a catheter for 2 weeks, and there is up to about a 10% chance of stricture."

In other series in which post-treatment biopsies have been performed to assess the success of the Ablatherm system, "Almost 90% of patients have negative biopsies following HIFU," Dr, Pinthus said. "What is really important is the PSA nadir. The median was very low in our study, 0.06 ng/mL, and that is very encouraging."

One of the co-authors of this study reports an investment interest in EDAP TMS.

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