Feel the heat: MR-guided focused US warms away bone tumor pain

A recently published study has confirmed that MR-guided focused ultrasound (US) can relieve pain and improve function in most patients with bone tumors who are not candidates for radiation treatment.

The study, the first completed phase III study of MR-guided focused US in oncology, was published online April 23 in the Journal of the National Cancer Institute.

Lead author Mark Hurwitz, MD, of the department of radiation oncology at Thomas Jefferson University in Philadelphia, and colleagues explained that focused US is a noninvasive technique that uses acoustic energy to heat lesions focally to between 65 and 85 degrees Celsius. “The combination of focused ultrasound with [MRI] enables physicians to perform precise localized tumor tissue ablation, while using MR thermometry for real-time temperature monitoring,” they wrote.

To test the palliative potential of MR-guided focused US, the authors evaluated a total of 147 patients from 17 centers in the U.S., Canada, Israel, Italy and Russia. One hundred twelve patients were randomly assigned to receive MR-guided focused US, while the remaining 35 patients received a sham placebo treatment in which the US device was not turned on.

Nearly two-thirds of the patients in the treatment arm reached the primary endpoint of self-reported pain improvement without an increase of medication three months after treatment and 47 percent were able to reduce or stop the use of opiod medications, according to Hurwitz and colleagues.

Since most patients in the treatment arm experienced pain relief and improved functioning within several days of treatment, those who didn’t respond to the placebo treatment within two weeks were allowed to be unblended and offered MR-guided focused US.

Most adverse events were resolved on the treatment day, with the most common complaint being sonication pain. More serious events included two patients who had pathological fractures, one who sustained a third-degree skin burn and one who suffered from neuropathy.

Hurwitz and colleagues noted the advantages of MR-guided focused US included the high-resolution images of the targeted tumor and nontargeted anatomy, accurate monitoring of temperatures and immediate post-treatment validation of the extent of ablation.

Next steps will be to refine treatment technique to improve response and to apply radiation and thermal therapy together, according to the authors.