Magnetic nanoparticle-mediated intracellular hyperthermia has been a largely experimental modality of hyperthermia, but this treatment modality has the potential to achieve tumor targeted heating without any side effects. The technique consists of targeting magnetic nanoparticles to tumor tissue and then applying an external alternating magnetic field to induce heat generation by the magnetic nanoparticles. Among available magnetic nanoparticles, magnetite has been extensively studied. Recent years have seen remarkable advances in magnetite nanoparticle-mediated hyperthermia ; both functional magnetite nanoparticles and alternating magnetic field generators have been developed. Currently, some researchers are attempting to begin clinical trials, suggesting that time may have come for clinical applications. This review describes recent advances in magnetite nanoparticle-mediated hyperthermia.

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Gemcitabine (GEM) has improved both overall survival and tumor-related symptoms in patients with advanced pancreatic cancer when compared to 5-FU, and is a widely accepted treatment for such patients. However, pancreatic cancers remain extremely resistant to chemotherapy. Empiric chemotherapy based on GEM has had no major successes in treating patients with advanced disease. The objective of this study was to evaluate the response rate, survival, and toxicity of the sequential combination of GEM and hyperthermia. Between November 2005 and November 2007, 7 patients with unresectable pancreatic cancer received sequential combination therapy with GEM and hyperthermia at the Matsushita Memorial Hospital. Data were then compared with 7 historical controls treated with GEM alone at the same institution. There were no significant differences in age, performance status or UICC stage between the GEM plus hyperthermia and GEM monotherapy groups. The disease control rate (CR+PR+SD) was 14.3% for patients treated GEM alone and 57.1% for patients treated with GEM plus hyperthermia. The median survival time was 198 days for patients treated with GEM alone, and 327 days for patients treated with GEM plus hyperthermia. Combination therapy with GEM and hyperthermia thus improves overall survival when compared with GEM monotherapy (p=0.0275). The sequential combination of GEM plus hyperthermia showed a potential therapeutic effect, and was at least as effective as GEM monotherapy. To clarify the effects of this combination therapy, a larger prospective clinical trial is required.

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This paper describes a potential new method to non-invasively heat a region in a human brain by using electromagnetic field patterns generated inside a resonant cavity and does not require any physical attachments to the subject. The purpose of the study described here is to demonstrate the ability of this method to heat a small defined region. This study utilized computer simulations and a current model of the new heating system. In this proposed heating method, a human head is placed in the gap of a re-entrant type resonant cavity. The brain tumor is heated through interactions with electromagnetic energy, and no contact is required between the surface of the head and the inner electrodes. The thermal properties of this proposed method when applied to agar phantoms were calculated with computer simulations, and these properties were checked experimentally with the current physical version of the heating system. The calculated temperatures were in close agreement with the measured temperatures with an error of 10% or less. The TM-like modes are similar to the transverse magnetic (TM) modes generated inside a cylinder type resonant cavity. To heat a defined region, two TM-like modes were tested on agar phantoms. The thermal images of the cylindrical agar and the agar head phantoms showed that the values for the temperature increases at the center of the heated agar phantoms using two modes, a TM₀₁₀-like mode and a TM₀₁₂-like mode, were 5.9°C and 8.0°C, respectively. The TM₀₁₀-like mode resulted in a larger area being heated than the TM₀₁₂-like mode. In experimental results, compared to the TM₀₁₀-like mode, the heated area with the TM₀₁₂-like mode was localized to approximately 50% of the area heated by the TM₀₁₀-like mode. These results suggest that the proposed heating method using electromagnetic field patterns generated inside of a resonant cavity is capable of being used for non-invasive brain tumor hyperthermia treatments.

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