A novel hyperthermia treatment for bone metastases using magnetic materials.

Patients with bone metastases in the extremities sometimes require surgical intervention to prevent deterioration of quality of life due to a pathological fracture. The use of localized radiotherapy combined with surgical reinforcement has been a gold standard for the treatment of bone metastases. However, radiotherapy sometimes induces soft tissue damage, including muscle induration and joint contracture. Moreover, cancer cells are not always radiosensitive. Hyperthermia has been studied since the 1940s using an experimental animal model to treat various types of advanced cancer, and studies have now reached the stage of clinical application, especially in conjunction with radiotherapy or chemotherapy. Nevertheless, bone metastases have several special properties which discourage oncologists from developing hyperthermic therapeutic strategies. First, the bone is located deep in the body, and has low thermal conductivity due to the thickness of cortical bone and the highly vascularized medulla. To address these issues, we developed new hyperthermic strategies which generate heat using magnetic materials under an alternating electromagnetic field, and started clinical application of this treatment modality. The purpose of this review is to summarize the latest studies on hyperthermic treatment in the field of musculoskeletal tumors, and to introduce the treatment strategy employing our novel hyperthermia approach.

Intraosseous lipoma of the third lumbar spine: a case report.

INTRODUCTION: Intraosseous lipoma is a benign bone tumor, and the tumor occurs more frequently in the lower extremities. We present a very rare case of intraosseous lipoma occurring in the lumbar vertebral arch and spinous process. CASE PRESENTATION: A 54-year-old Japanese man presented with a three-month history of lumbar pain. Magnetic resonance imaging of the L3 vertebral arch and spinous process revealed high intensity on T1- and T2-weighted imaging, and it was suppressed on fat-suppression imaging and no enhancement showed on gadolinium contrast-enhanced imaging. Computed tomography imaging revealed an osteolytic change accompanied by marginal osteosclerosis in his third lumbar vertebral arch and spinous process, as well as a thinned and bulging bone cortex. An analgesic had been administered prior to his visit, but low back pain had persisted, so we performed curettage and filled the defect with hydroxyapatite bone. His low back pain was improved immediately after surgery, and no recurrence of tumor has been observed on computed tomography imaging as of three years postoperatively. CONCLUSIONS: Symptomatic intraosseous lipoma of spine is very rare, but the patient may be surgically well-treated by curettage and reconstruction of the benign tumor.

Polyacrylamide gel containing egg white as new model for irradiation experiments using focused ultrasound.

A polyacrylamide (PAA) gel containing egg white as a new model for irradiation experiments in high-intensity focused ultrasound HIFU is introduced. The gel is transparent except in thermally necrosed regions which are white. The model is similar to, and has the same benefits as, gels containing bovine serum albumin (BSA) protein, but egg is less expensive than BSA. The acoustic properties of the gel are very favorable, similar to those of soft tissues; density 1.0 g/cm(3), sound speed 1540 m/s and acoustic attenuation 0.4 dB/cm at 2 MHz. We illustrate the usefulness of the gel in visualizing HIFU lesions and introduce a new model of gastric submucosal tumor in a rabbit stomach, showing that this gel can be formed into any desired shape. Our PAA gel containing egg white is an attractive candidate for a disposable acoustic material suitable for experimental applications of HIFU.

Mixture ratios of local bone to artificial bone in lumbar posterolateral fusion.

There have been no reports on the effects of the mixture ratio of local bone graft to artificial bone on the outcome of intervertebral bone fusion. The purpose of this study was to determine whether the mixture ratio of local bone removed from laminae and spinous processes to apatite- and wollastonite-containing glass ceramic (AWGC) granules affected fusion rates in spinal fusion. Posterolateral lumbar fusion at two levels without spinal instrumentation was performed in 35 patients who were diagnosed with lumbar spinal canal stenosis. The patients were randomly divided into three groups, each of which received a different mixture ratio of local bone to AWGC granules: 2:1, 1:1, and 1:2. The total mass of grafted bone was 20 g in all three groups. The fusion rate was approximately 80% in all three groups. Our results indicate that lumbar posterolateral fusion can be successfully achieved even when the mixture ratio of local bone graft to AWGC granules is 1:2.

Effect of hyperthermia by magnetite cement on tumor-induced bone destruction.

Our study focuses on the antineoplasmic action of hyperthermia. In this study, use of a heat-generating cement was exploited for the management of pathological and impending fractures in malignancies. The cement contains magnetic powder in ceramic particles and generates well-regulated heat when a magnetic field is applied externally. Eighteen rabbits were inoculated with blocks of VX2 tumor into one of their tibia. One week after the procedure, 9 rabbits were exposed to a magnetic field (HT group) while the remaining 9 rabbits were not (non-HT group). In rabbits killed between 20 and 42 days after the VX2 inoculation, the circumference of the operated leg was 7.9 +/- 0.3 cm and 10.2 +/- 1.0 cm (mean +/- SE) in HT and non-HT groups, respectively ( P < 0.05). Histological findings revealed the regressive change in tumor tissue of the HT group. By radiographs, pathological fractures and cortical bone destruction were seen in 5 and 8 rabbits in the non-HT group, respectively, but in the HT group these effects were absent in all the rabbits except 1 in which a definite diagnosis has not been made. Our findings demonstrate that controlled hyperthermia therapy using a newly developed bone cement suppresses tumor growth and prevents local bone destruction caused by VX2 tumors.