Treatment of breast cancers by magnetic thermoablation: in vivo experiments in mice

I. Hilger¹ - W. Andrä² - R. Hergt² - R. Hiergeist² - W. A. Kaiser¹

¹ Institut für Diagnostische und Interventionelle Radiologie des Klinikums der Friederich-Schiller-Universität Jena, D-07740 Jena, Germany
² Institut für Physikalische Hochtechnologie e.V., D-07745 Jena, Germany

Abstract
The objective of the present study was to investigate the feasibility of a minimal-invasive method for the elimination of tumors in the breast by local heating. Heating is generated by an intratumoral iron oxide (magnetite) loading of the tumor and exposure of the breast to an alternating magnetic field. The methodology consisted in the implantation of human adenocarcinomas (MX-1 cells) into 10 immunodeficient mice. After application of coated iron oxide particles (average total particle diameter: 10 nm) the intratumoral particle deposition was controlled by radiography. Iron contents in selected organs were determined using atomic absorption spectrometry at 50 min p.i.. During exposure of mice (4 min) to an AC magnetic field (frequency: 400 kHz, amplitude: 6.5 kA/m) intratumoral and rectal temperatures were measured. 6.7±2.3%; 2.8± 0.9% and 2.4 ± 0.1\0f injected iron dose per g dried tissue was found in the spleen, liver and blood, respectively at 50 min p.i.. No injected iron was found in the lung. Temperatures of 87 ±7^°C and 71 ±8^°C (distal and proximal tumor periphery, respectively) were measured at the end of magnetic field exposure. From the data we deduce that the method enables the generation of localized heat spots that damage tumor cells within several minutes and that the prototype particles are adequately retained at the tumor site. The introduction of the technique in future interventional radiological procedures is promising. Tables 1, Figs 4, Refs 14.