Abstract
In 1984 we developed a method of hyperthermia using Nd:YAG laser (laserthermia) for transmitting continuous low power energy (2W) through an artificial sapphire interstitial probe for local hyperthermia (43±0.5°C). Our experimental and clinical evidence indicated that this method is safe and effective. The process of tumor destruction induced by laserthermia is, however, poorly understood.
We performed both light microscopic and electron microscopic observations after laserthermia in vivo, and a comparative study of laserthermia, microwave hyperthermia and heating alone on the cytocidal effects in vitro, and obtained the following results; 1) At the tissue level, the initial change after laserthermia was damage of tumor feeding vessels. 2) At the cellular level, immediately after laserthermia the mitochondria in the intracellular organella were completely destroyed. 3) In in vitro studies, laserthermia demonstrated the most notable decrease in viability. In conclusion, as for the mechanism of laserthermia, it seems that the immediate of feet is cellular damage caused by both heat energy and Nd:YAG laser light followed by subsequent damage of tumor vessels.
