Effect of Local Hyperthermia Induced by 2450 MHz Microwave on EATC Tumor in ICR Mice

Hyperthemia induced 2450 MHz microwave was focused locally upon EATC tumor implanted in the foot of ICR mouse, when the tumor reached about 6mm in diameter. Normal skin reaction of the foot of the mouse on localized hyperthermia induced this apparatus was stronger than that on water bath, and so hyperthermia at 42℃ for 15 minutes was the maximum way for heating. Changes in regional blood flow volume of normal and tumor tissue following hyperthermia were observed by using^<133> Xe local clearance method. The blood flow of the tumor after heating by this apparatus decreased more remarkably than that on water bath, and decreased more than that of intact foot as heating temperature rose. Both of the stronger skin reaction and more decreased tumor blood flow, compared with the water bath, were seemed to suggest existence of the so-called hot spot effect. Hyperthermia induced by 2450 MHz microwave at 42℃ for 15 minutes delayed tumor growth (P<0.05) and showed a similar effect due to the water bath at 42℃ for 30 minutes. Enhancement of the local tumor control effect of X-ray-irradiation was also shown (P<0.01).