Novel hyperthermia for metastatic bone tumors with magnetic materials by generating an alternating electromagnetic field

We have developed a novel hyperthermic treatment modality using magnetic materials for metastatic bone tumors. The purpose of this study is to show the results of novel hyperthermia for metastatic bone tumors. This novel hyperthermic treatment modality was used for 15 patients with 16 metastatic bone lesions. In seven lesions, after curettage of the metastatic lesion followed by reinforcement with a metal intramedullary nail or plate, calcium phosphate cement (CPC) containing powdery Fe₃O₄ was implanted into the cavity. In one lesion, prosthetic reconstruction was then performed after an intralesional tumor excision. For the remaining eight lesions, metal intramedullary nails were inserted into the affected bone. Hyperthermic therapy was started at 1 week postoperatively. To comparatively evaluate the radiographic results of patients who underwent hyperthermia (HT group), we also assessed eight patients who received a palliative operation without either radiotherapy or hyperthermia (Op group), and 22 patients who received operation in combination with postoperative radiotherapy (Op + RT group). In HT group, all patients had an acceptable limb function with pain relief without any complications. On radiographs, 87, 38, and 91% were, respectively, considered to demonstrate an effective treatment outcome in HT group, Op group, and Op + RT group. The patients in HT group showed a statistically better radiographic outcome than the patients in Op group (P = 0.0042). But when compared between HT group and Op + RT group, there were no significant difference (P = 0.412). This first series of clinical hyperthermia using magnetic materials achieved good local control of metastatic bone lesion.