Minimally invasive techniques for pain palliation in extraspinal bone metastases: a review of magnetic resonance imaging-guided focused ultrasound (MRgFUS) and series conclusion

Abstract

Minimally invasive techniques are an effective primary or alternative modality for pain palliation in extraspinal bone metastases, particularly when conventional therapies, such as localized radiation therapy, leave a subset of patients with refractory pain. Previous issues in this series have reviewed outcome literature demonstrating the efficacy and safety profile of cryoablation, cementoplasty, radiofrequency ablation, embolization, laser photocoagulation, ethanol ablation, and microwave ablation. The newest technique, magnetic resonance imaging-guided focused ultrasound (MRgFUS), delivers nonionizing ultrasound energy in a noninvasive manner to produce thermal damage to the periosteum of bone metastases. This technique has previously demonstrated success in the treatment of uterine fibroids, movement disorders, solid tumors, desmoid tumors, and benign bone tumors. In extraspinal bone metastases, substantial pain relief has been achieved within 3 days and up to 12 mo after treatment, and this technique has shown success in lytic, blastic, and mixed lesions. The most common adverse effects are transient, short-lived procedural pain and minor skin burns. There is also promising evidence supporting its ability to reduce tumor volume. Future investigations will likely include evaluating its role in local tumor control and comparing it to localized radiation therapy. For all of these minimally invasive techniques, the majority of reported series are retrospective and small. Future multicenter, prospective, randomized trials are needed to compare the efficacy of these treatments to each other, and to conventional therapies.