Evaluation of magnetic fluid hyperthermia in a standard rat model of prostate cancer

PURPOSE: To examine the feasibility and potential of magnetic fluid hyperthermia (MFH) as a minimally invasive method for hyperthermia treatment of prostate cancer. MATERIALS AND METHODS: Orthotopic Dunning R3327 prostate tumors were induced in 20 male Copenhagen rats. The animals either received MFH treatment following intratumoral administration of magnetic fluids or were used as either tumor growth controls for determination of iron distribution in selected organs or as histologic controls without MFH treatment. The MFH treatments were carried out at 45 degrees C or 50 degrees C using an AC magnetic field applicator system designed for small animals. RESULTS: Sequential treatments with MFH were possible following a single intratumoral injection of magnetic fluid. Intratumoral temperatures of 50 degrees C and more were obtained and were monitored online using fluoro-optic thermometry. Four days after MFH treatments, 79% of the injected dose of ferrites was still present in the prostate. CONCLUSIONS: The successful intraprostatic nanoparticle infiltration and stable steady-state intratumoral treatment temperatures demonstrate the feasibility of MFH in a prostate cancer model. Efficacy and survival benefit must be confirmed in further experiments.