Development of a second-generation radiofrequency ablation using sintered MgFe(2)O(4) needles and alternating...

Magnetic metal particles are known to induce heat energy under an alternating magnetic field (AMF). We developed a local tumor-heating device incorporating an MgFe(2)O(4) needle for the purpose of mild ablation for cancer treatment. A needle made from sintered MgFe(2)O(4) particles was embedded in the hepatic or breast tumors. Tumors were then heated by the energy dissipated from the needle exposed to an AMF. We sequentially evaluated histological changes, cellular activity of tumors, and the extent of thermal effect using nicotinamide adenine dinucleotide (NADH) diaphorase and terminal deoxynucleotidyl tranferase-mediated digoxigenin-DUTP nick-end labeling (TUNEL) staining. The mean temperature of the tumor tissue during heating was about 60 degrees C. Nuclei of the tumor cells became hyper-chromatin immediately after heating. The injured area spread progressively until 3 days after heating; when the area was surrounded by fibroblasts (meaning is not clear). Tumors disappeared after treatment without complications. This is the first time that the complete death of tumor cells has been realized by raising the tumor temperature above 60 degrees C using the heat generated by magnetic metal particles exposed to AMF. This device may be useful in the future for local hyperthemic treatment of human cancers.