Pain Palliation of Bone Metastases Using Magnetic Resonance Guided Focused Ultrasound - Multi-Center Multi-trial Results

ABSTRACT Introduction Magnetic Resonance guided Focused Ultrasound (MRgFUS) is a non-invasive, non-ionizing treatment for thermal ablation of tumors. The technology uses high intensity focused ultrasound ablation combined with continuous MR imaging to denervate pain. Precise targeting of the lesion and real time monitoring of tissue temperature rise are cornerstones of the technique. We present here results of multiple multi-center studies evaluating the safety and effectiveness of MRgFUS for painful bone metastases. Methods 93 patients with painful bone metastases underwent MRgFUS in 14 medical centers worldwide. Treated lesions had to be remote from nervous structures or joints. Effectiveness of pain palliation was evaluated with a standardized 11-point pain rating scale (0-no pain/10-worst pain) and by monitoring changes in pain-relieving medication. A reduction of 2 points or more was considered a significant response. Safety events were recorded and evaluated by severity. Results of 31 patients treated in initial safety studies were previously reported by Liberman et al (Ann Surg Oncol. 2009 Jan; 16(1):140-6). Results 107 procedures were performed, targeting 96 lesions in 93 patients. 3 patients were treated twice targeting a different lesion; another 11 patients underwent a second treatment due to large lesions. Patients were followed-up for a period of 3 months. Pain response was relatively rapid: within 3 days, on average, the clinical endpoint was met and maintained. Pain scores averaged 6.9 pre-treatment, decreased to 4.5 within 3 days post-treatment, to 3.3 at one month post-treatment, and further decreased to 2.6 at three month follow-up. There were no serious adverse events related to the treatment. 2 patients had mild skin erythema following the treatment and 5 patients (5%) had pain progression. Our updated results are similar to early reports. Conclusions The presented results clearly show that MRgFUS can provide a quick, effective and safe palliative therapy for patients suffering from painful bone metastases. Current results are consistent with initial reported results. Randomized trials are being conducted in patients as a first line treatment of painful bone metastases vs. radiation therapy and in patients who failed radiation therapy vs. sham. Disclosure L. Shay Levi: I work in InSightec as the global bone applications specialist. InSightec is the company sponsered these clinical trials. All other authors have declared no conflicts of interest.