By Charlie Schmidt
There are many ways to kill prostate cancer cells. Radiation and chemotherapy are the most widely used. Freezing (cryotherapy) is another. A French company wanted to add heat generated by ultrasound waves to the armamentarium, but an FDA advisory panel has said “no.”
The heat technique, known as high-intensity focused ultrasound (HIFU), is being used in several countries for treating localized prostate cancer. To administer high-intensity focused ultrasound, a doctor inserts an ultrasound probe into the rectum, then focuses beams of sound waves on cancerous portions of the gland. Supporters say that high-intensity focused ultrasound offers a noninvasive (meaning nonsurgical) way to target cancer cells that won’t damage the nerves that control a man’s ability to have an erection.
As part of its standard review process for all new devices, the FDA convened a panel of experts whose job was to assess the available data on the safety and effectiveness of HIFU for localized prostate cancer.
The panel looked at publications on HIFU in the scientific literature. It also reviewed results from an unfinished clinical trial comparing high-intensity focused ultrasound treatment for early prostate cancer with cryotherapy. (Like HIFU, cryotherapy is also a noninvasive treatment.) Known as the U.S. Pivotal Study, this trial was launched in 2012 but never met its goal to recruit 205 men for each treatment arm. When the trial was cancelled earlier this year, only 135 men had been treated with high-intensity focused ultrasound and just 5 men had been treated with cryotherapy.
Unpublished results showed that high-intensity focused ultrasound was not highly effective. Nearly one in three prostates treated with HIFU tested positive for cancer in biopsies taken two years after treatment. It also posed a high risk of side effects, with more than half of the men treated with high-intensity focused ultrasound experiencing erectile dysfunction, urinary retention, incontinence, or other health problems.
The FDA generally heeds recommendations from its advisory panels—a strong indication that high-intensity focused ultrasound will not be approved here any time soon. “In our view, HIFU in this country has reached the end of the line,” says Eric Klein, a panelist and chairman of the Glickman Urological and Kidney Institute at the Cleveland Clinic. The French company that was seeking the FDA’s okay, or another company, could apply again with more complete or persuasive data.
Since men with localized prostate cancer might also be candidates for active surveillance, which spares them from side effects like erectile dysfunction and incontinence, “it would be difficult for me as a practicing physician to recommend that they be treated with HIFU,” says FDA panelist and prostate cancer specialist Dr. Marc B. Garnick, the Gorman Brothers Professor of Medicine at Harvard Medical School and Beth Israel Deaconess Medical Center, and Editor in Chief of Harvard Medical School’s 2014 Annual Report on Prostate Diseases.
Whether the FDA panel’s denial will affect the availability of high-intensity focused ultrasound outside the U.S. is unknown, says Garnick, given that other countries base the approval of medical treatments, and in some cases the availability, on their own criteria. “And other potential indications for HIFU in the United States are still being studied,” Garnick says.