Doctors Study Non-Invasive, Radiation-Free Technology as Pain-Killing Treatment for Bone Metastases

Doctors Study Non-Invasive, Radiation-Free Technology as Pain-Killing Treatment for Bone Metastases
Trial name: ExAblate Treatment of Metastatic Bone Tumors for the Palliation of Pain

When prostate cancer spreads, it seeks new organs in the body to attack. One of the most common targets: the skeleton. When tumors form on bones, these "metastases" can cause pain and significant problems that severely impact quality of a patient's life.

Now, doctors are studying innovative sound wave-based technology to determine if the completely non-invasive, radiation free procedure will relieve the pain from bone metastases without the side effects seen with current treatments.

"Pain from tumors that have spread to the bone is the most common kind of pain for cancer patients," notes Dr. Mark Hurwitz of the Dana-Farber/Brigham & Women's Cancer Center at Harvard Medical School and President of the Society for Thermal Medicine. "While maintaining quality of life for patients with advanced cancer is a top priority, current palliative treatments have several limitations. When pain persists or recurs after palliative radiation, options are often limited as many patients are too weak to withstand invasive procedures to quell their pain."

Physicians have been treating uterine fibroid tumors with focused ultrasound technology since 2004 and now Hurwitz and doctors at other leading cancer centers are applying this technology, which works in concert with magnetic resonance imaging (MRI), to bone metastases in a study being conducted at leading cancer centers across the U.S. The technology, known as the ExAblate system, has shown promising efficacy and safety results in pain palliation feasibility studies in with bone metastases and the researchers hope to confirm the those results though this larger trial.

"We look forward to participating in this pivotal study which could provide us with a non-invasive and effective way to improve late-stage cancer patients' quality of life," Hurwitz said.

Bone metastases will cause many late-stage prostate cancer patients severe pain, forcing many to take opioid painkillers, which are not only addictive, but can cause severe, debilitating constipation.

Other pain relieving treatments exist, but many carry significant side effects. Some treatments require invasive surgery, while others run the risk of damaging the healthy tissue surrounding the metastases; drugs can affect the patient’s feeling of well being. Some treatments are effective for some patients and not for others. External beam radiation therapy (EBRT) fails to reduce pain in 30% of the patients it is used to treat making the need for optimal second line therapies important.

MRgFUS works by combining MRI and ultrasound technology. An MRI is used to map out the body and determine where the ultrasound waves will be focused. Focusing ultrasound waves is similar to focusing the sun’s rays through a magnifying glass: whatever the waves are focused on will be burned. By aiming the ultrasound at the bone periosteum, the ExAblate will destroy the nerve endings of the bone, so that the patient no longer feels the pain caused by the tumor. While the bone tumor remains, this is nonetheless a powerful palliative method to reduce the pain felt by the patient. Additionally, because MRgFUS is not radioactive, it can be administered repeatedly, and to the same sites if necessary.

To qualify for the study, patients' pain must have returned or never subsided after an initial round of palliative radiation treatment or the patient must have been unable to receive radiation treatment in the first place.

Clinical trials are being held at Brigham & Women’s Hospital in Boston; the Fox Chase Cancer Center in Philadelphia; Houston Methodist in Houston, TX; Lahey Clinic in Burlington, MA; University Health Network in Toronto; Sheba Medical Center in Israel; Sightline Medical Center-Houston; the University of California, Los Angeles (UCLA); the University of California, San Diego (UCSD) Medical Center in San Diego, CA; and Weill Cornell Medical College in New York. Memorial Sloan Kettering Cancer Center in New York is also expected to participate in the study.

In a previous trial conducted at sites in Israel, Toronto, Germany and the United Kingdom, most patients who underwent MRgFUS treatment noticed a fast reduction in pain. Patients indicated great acceptance of the procedure.

"If this study does indeed provide us with a new alternative to treating metastases, that would be a breakthrough," Hurwitz said. "A noninvasive treatment that could be administered repeatedly without harming the healthy tissue surrounding the tumor could be the solution to the problem of finding a treatment precise and effective enough to alleviate the pain of metastases, without overwhelming patients in an already weakened state."