High Frequency Ultrasound (HIFU)

Last Modified: March 15, 2006

Dear OncoLink "Ask The Experts,"

I have recently heard about HIFU treatments for prostate cancer. What can you tell me about this?

Richard Whittington, MD, Associate Professor of Radiation Oncology at the University of Pennsylvania School of Medicine, responds:

This technique uses focused ultrasound to heat small segments of the prostate. Hyperthermia units with similar heating effects were tried in the past and failed, but this new approach may be better.

In the US, there has only been one completed Phase I trial investigating whether or not this technique is safe. A Phase II study to evaluate the effectiveness of this treatment has not yet started. The Japanese and European reports look good, but they both excluded patients that didn't "heat well", which happens in about 5-10% of patients in most series. The studies don't score these cases as treatment failures, even though they started the procedure and the patient wasn't cured -- which in my mind is still a treatment failure. The study researchers also needed to take half of the patients back for a second procedure, but they don't count that as treatment failure either, even though the first procedure did not cure the patient.

With all of this, the median follow-up of survivors in most series is less than 18 months, which is too short to evaluate long-term control of the tumor. The HIFU company claims that this technique works best in stage T1c or T2a tumors, with poor results in T2b and T2c cancers. There are also somewhat better results with a PSA <10 as opposed to PSA >20. There did not appear to be a Gleason score effect on outcomes. The toxicity in most series is low. However, prostate cancers typically arise in the periphery of the gland, so the ultrasound has to heat to that distance without burning the tissue 1 or 2 mm further out. It may play a role in recurrences after radiation therapy or cryotherapy, but its role in primary therapy is unproven as of yet.