Magnetic-resonance-guided focused ultrasound (MRgFUS) is non-inferior to external-beam radiation therapy (EBRT) for the treatment of patients with painful bone metastases, according to results of a randomised, controlled trial presented at the 2018 European Congress of Radiology (ECR). Although MRgFUS is limited to non-spinal locations, it is a radiation-free, single-session procedure.
High-intensity focused ultrasound as an image-guided intervention that is non-invasive and shows low complication rates. It has also been shown to provide accurate location and real-time thermal feedback. “Both of these features allow for improved safety and efficacy profile,” explained lead author Alessandro Napoli, MD, PhD, ‘La Sapienza’ University of Rome, Rome, Italy, speaking here today.
Studies have recently shown that MRgFUS can provide pain palliation and local tumour control for patients with bone metastases. In the current study, the aim was to define the clinical outcomes derived from MRgFUS in direct comparison with EBRT in patients with painful bone metastases.
The researchers enrolled 233 adults (male 53.7%) with a life expectancy greater than 3 months and radiologically proven bone metastases and no radiotherapy treatment within the previous 1 month. Pain visual analogue score (VAS) was 4 or greater irrespective of medication. A vertebral location was excluded for the metastases, as a limit to the use of MRgFUS.
The patients randomised to EBRT (n = 117) or MRgFUS (n = 116) demonstrated mainly primary prostate (37.8%), breast (33.5%), lung (18.9%), and colon (6.9%) cancers.
The primary endpoint was for treatment response, as reduction in VAS worst pain of ≥2 points, with stable or reduced opioid use, compared with baseline. This endpoint was met for 72 (61.6%) patients treated with EBRT, and 90 (77.6%) treated with MRgFUS, indicating the non-inferiority of MRgFUS for palliative purposes (adjusted odds ratio, 1.07; P = .818).
A per protocol analysis at 6 months demonstrated 28.6% versus 65.0% combined complete and partial responders.
There were significantly greater deaths in the radiotherapy group from 3 months (30.6% vs 0%) and to 6 months (59.2% vs 25.0%). “This is something that we need to discuss — whether this was something associated with toxicity or was just bias of the randomisation,” Dr. Napoli noted.
Although the survival analysis demonstrated significant benefit over EBRT for MRgFUS at 6 months (P = .0034), by the end of follow-up at 12 months, this difference was lost.
For the range of secondary endpoints, there were no significant differences between these treatments in terms of average pain, pain interference with activity, breakthrough pain, mood, or patient quality of life.
The researchers concluded that MRgFUS represents a valid treatment option in the management of painful bone metastases that are technically accessible.
Dr. Napoli noted, “We can also treat patients during chemotherapy administration, which is very important.”