Primary Bone Malignancy: Effective Treatment with High-Intensity Focused Ultrasound Ablation

PURPOSE: To evaluate the long-term follow-up results of ultrasonographically (US)-guided high-intensity focused ultrasound ablation in patients with primary bone malignancy. MATERIALS AND METHODS: The study was approved by the ethics committee. Each patient or parent (if patient was younger than 18 years), signed an informed consent form before being selected and treated. From December 1997 to November 2004, 80 patients with a primary bone malignancy-60 with stage IIb disease and 20 with stage III disease (Enneking staging system)-were treated with US-guided high-intensity focused ultrasound ablation. High-intensity focused ultrasound ablation combined with chemotherapy was performed in 62 patients with osteosarcoma, one patient with periosteal osteosarcoma, and three patients with Ewing sarcoma. The remaining 14 patients had chondrosarcoma, giant cell bone cancer, periosteal sarcoma, or an unknown malignancy and were treated with high-intensity focused ultrasound ablation only. Magnetic resonance (MR) imaging or computed tomography (CT), and single photon emission computed tomography (SPECT) were used to assess tumor response. Cumulative survival rates were calculated by using the Kaplan-Meier method. Adverse effects were recorded. RESULTS: High-intensity focused ultrasound ablation guided by real-time US was performed. Follow-up images demonstrated completely ablated malignant bone tumors in 69 patients and greater than 50% tumor ablation in the remaining 11 patients. Overall survival rates at 1, 2, 3, 4, and 5 years were 89.8%, 72.3%, 60.5%, 50.5%, and 50.5%, respectively. Survival rates at 1, 2, 3, 4, and 5 years were 93.3%, 82.4%, 75.0%, 63.7%, and 63.7%, respectively, in the patients with stage IIb cancer and 79.2%, 42.2%, 21.1%, 15.8%, and 15.8%, respectively, in those with stage III disease. Among the patients with stage IIb disease, long-term survival rates were substantially improved in the 30 patients who received the full treatment-that is, complete high-intensity focused ultrasound and full cycles of chemotherapy-compared with the survival rates for the 24 patients who did not finish the chemotherapy cycles and the six patients who underwent partial ablation only. Only five (7%) of the 69 patients who underwent complete ablation had local cancer recurrence during the follow-up period. Forty adverse events were recorded, with 14 patients requiring surgical intervention. CONCLUSION: US-guided high-intensity focused ultrasound ablation of malignant bone tumors is feasible and effective and eventually may be a component of limb-sparing techniques for patients with these cancers.