When cancer spreads to the bones, patients often suffer debilitating pain. Now, the results of a newly published phase III clinical trial show that magnetic resonance guided focused ultrasound treatment that heats the cancer within the bone, relieves pain and improves function for most patients when other treatment options are limited. (MD Hurwitz et al., Magnetic Resonance–Guided Focused Ultrasound for Patients With Painful Bone Metastases: Phase III Trial Results, J Natl Cancer Inst, 2014; doi: 10.1093). This is the first phase III study to use this technology in the treatment of cancer, “ says the study’s principal investigator and lead author Dr M. Hurwitz of the department of Radiation Oncology at Thomas Jefferson University. Although radiation therapy is commonly used to treat bone-related pain and is effective for most patients, not all patients experience pain relief and over time those who do may have recurrence of pain. In addition, it’s possible for a patient to receive the maximum radiation dose that can be safely delivered without fully controlling the pain. In situations where radiation therapy is not an option, alternative treatments are required. A total of 147 patients from 17 centers in the U.S., Canada, Israel, Italy, and Russia were enrolled in the study and randomized to undergo MRgFUS or a placebo treatment. Patients in the treatment group received focused ultrasound precisely targeted to their bone tumors to heat the tumor tissue to between 65 and 85 degrees Celsius, resulting in its destruction. During each treatment, the patients were monitored real-time via magnetic resonance imaging (MRI) to ensure the correct tissue was targeted and the right temperatures were reached while ensuring heat in surrounding normal tissues and organs remained at safe levels. Patients who did not respond to the placebo treatment within two weeks were allowed to be unblinded and offered MRgFUS. Patients responded well to treatment, with 64 percent experiencing either no pain or a significant reduction in their pain at three months as measured by a 2 point or greater decrease in the numeric rating score (NRS) for pain, the clinically validated measurement tool. Many patients were able to reduce or stop use of opiod medications. Notably, most patients experienced pain relief and improved functioning within several days of treatment.