ASCO: Rapid, Durable Bone Met Pain Relief With MR Guided Focused Ultrasound

CHICAGO-The use of magnetic resonance–guided focused ultrasound (MRgFUS) ablation therapy for the management of painful bone metastases resulted in a high rate of pain response that was rapid, durable, and clinically meaningful, according to an abstract presented at the 2013 ASCO Annual Meeting in Chicago. In fact, 67% of patients had significant reductions in pain after receiving the treatment, which uses numerous small ultrasound beams designed to converge on a tumor within bone, heat it, and destroy it.

“MR-guided focused ultrasound is an attractive treatment option in the management of painful bone metastases, particularly for patients with otherwise limited treatment options,” said presenter Mark Hurwitz, MD, director of thermal oncology for the department of radiation oncology at Thomas Jefferson University Hospital.

The study was a phase III, multicenter study that randomly assigned patients 3:1 to MRgFUS or placebo. The primary endpoint was a two point or greater improvement (in numerical rating scale [NRS] worst pain score) by 3 months in more than 50% of MRgFUS-treated patients, and a significantly increased response rate on the MRgFUS arm. The researchers also examined quality of life and toxicity.

The study included 142 patients in whom radiation was not a primary treatment option, and who had an NRS score of four or greater despite optimization of their medication regimen.

At 3 months, 65% of patients on the focused ultrasound experienced a significant benefit of at least a two-point change in NRS in comparison with 19% on the placebo arm. Also of note, 44% on the focused ultrasound arm compared with 14% on the placebo arm were able to either decrease or stop their narcotic medications.

Patients on MRgFUS also had a rapid improvement in their pain score, typically within a few days of treatment, Dr. Hurwitz said.

“A comparison of worst pain score as measured by the NRS scale showed that from a baseline of seven, a two-point improvement was achieved within days on the study arm and there was continued improvement throughout the first month, and this improvement was maintained for the study duration,” Dr. Hurwitz said. “Ultimately, there was nearly a four-point decrease in the NRS.”

Quality of life was also improved in the study arm. A clinically significant improvement at 3 months in Brief Pain Inventory–Quality of Life score for MRgFUS but not sham treatment was noted (average change: 2.4 vs 0.2, respectively; P < .0001).

According to Dr. Hurwitz, the treatment was well tolerated. Adverse events were limited with the exception of pain or discomfort associated with the procedure or shortly thereafter. For most patients, this was transient and limited to the procedure itself.

“MR-guided focused ultrasound should be considered a primary treatment option in settings where radiation therapy is not considered an attractive option,” Dr. Hurwitz said.

Discussant Mary Uan-Sian Feng, MD, of the Comprehensive Cancer Center at the University of Michigan Health System, acknowledged that the study showed significant improvements in pain, but questioned the long-term local control.

“As you know, bone metastases can not only cause pain, but also skeletal instability and neurologic compromise,” Dr. Feng said. “We need to see longer follow-up.”