Cryosurgery and hyperthermia treatment, which is an operation method that uses the vital reaction of tissue by applying the effect of temperature, are used as a treatment method for warts and malignant tumors. Since liquid nitrogen and argon gas are used as the cryogen, for example, it is difficult to control the freezing rate and thawing rate. In hyperthermia, there are problems of thermotolerance acquisition by heat shock protein (HSP) expression and only a few studies regarding hyperthermia with cryosurgery have been investigated. The aims in this study are to produce a rate controllable cryosurgery system and evaluate hyperthermia after cryosurgery by comparing cryosurgery on the mouse liver. A contact-type operation system including a free-piston Stirling cooler (FPSC) and peltier device was used, applying a 1-cycle rapid freezing and slow thawing method for cryosurgery, and hyperthermia followed cryosurgery. The temperatures of the tissue surface and probe were measured using thermocouples during the operation, the mouse liver was stained by Hematoxylin-Eosin (HE) after the operation and observed under an optical microscope. The results showed measured temperatures of rapid freezing, slow thawing and heating tissue following cryosurgery: minimum temperature reached was -18.9 and -18.6°C in cryosurgery and hyperthermia groups, respectively, and the maximum temperatures measured in the hyperthermia group were 38.3°C at the center point of the liver surface in the probe contact area and 34.1°C at 5 mm from center. HE-stained tissue showed stasis, decreasing stainability and disappearance of cell nucleus in both groups. But in the hyperthermia after cryosurgery group, the disappearance of cell nucleus occurred more on the liver surface tissue in the neighborhood of the probe contact area. This suggests that the effect of hyperthermia after cryosurgery would be an effective treatment, and hyperthermia treatment after cryosurgery may contribute to the development of cryosurgery in the future. HSP analysis is currently underway, and the results will be reported upon completion.
