MR-Guided, Focused Ultrasound Targeted at Bone Metastases Helps Ease Pain

A high-dose of ultrasound targeted to painful bone metastases appears to rapidly bring patients relief, and with largely bearable side effects.

The new study’s findings were presented by Fox Chase Cancer Center (Philadelphia, PA, USA) scientists at the 49th annual meeting of the American Society of Clinical Oncology (ASCO), on June 3, 2013, held in Chicago (IL, USA). During the procedure, known as magnetic resonance (MR)-guided, focused ultrasound, doctors direct a concentrated beam of energy to certain nerve endings that are causing pain in bone metastases. These patients typically have a significant amount of discomfort—50% of study participants rated their pain at least a 7 out of 10—but within several days, most reported they felt substantial relief.

Although Fox Chase patients received local anesthesia during the procedure, the most typically reported side effect was pain, which can often be lessened with additional anesthesia, according to study author Joshua Meyer, MD, attending physician in the radiation oncology department at Fox Chase. “That’s temporary pain, which is gone as soon as the procedure is over,” he said. “The whole reason we’re doing the procedure is for the pain relief that comes afterwards. And that’s relatively quick—we see a response by a day or so, and within three days of the procedure most patients are reporting a significant improvement.”

Specifically, 67% of the 107 treated patients said their pain was “much improved” after the treatment, and that relief continued through the end of the three-month study. In comparison, among a group of 35 patients that received a placebo (sham) treatment only 20% reported some pain relief, Dr. Meyer and his colleagues reported.

Patients enter into an MRI unit during the procedure, which allows clinicians to direct a cone of ultrasound energy at specific, targeted bone sites that are causing pain. The MRI also acts as a thermometer to gauge the temperature deep within the body created by the high dose of energy, which generates enough heat to burn the nerve endings that are causing pain. Although pain relief was sustained until the end of the study at 90 days, it’s not clear how much longer the pain relief lasts, reported Dr. Meyer. “We’ve had reports of patients experiencing pain relief up to a year or more outside of the study.”

Typically, patients with bone metastases are treated with radiation, which shrinks the bone cancer that is putting pressure on nerve endings, causing pain. This technique also treats the cancer (MR-guided focused ultrasound may not), but typically takes weeks before patients experience pain relief, and not all will respond, stated Dr. Meyer. Moreover, others may not be eligible to receive further radiation, if they have limited bone marrow function, for instance, he noted. The latest studies did not compare the effectiveness of the ultrasound technique to radiation, but the response to ultrasound appears “within the same ballpark of that in previous studies with radiation.”

MR-guided focused ultrasound has been approved by the US Food and Drug Administration (FDA), and is available at Fox Chase Cancer Center, as well as a handful of other facilities around the country.


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