High-temperature hyperthermia (HTH) is an established treatment option for cancer. The aim of the present study was to reveal the exact correlation between HTH at temperatures of 50-70°C and the resulting antitumor effects, using a glioma rat model. In the 60°C (T-60) and 70°C (T-70) HTH groups, tumor growth rates were significantly suppressed compared with those in the nontreatment (NT) group. In the 50°C (T-50) HTH group, tumor growth rates were not suppressed compared with those in the NT group. The numbers of terminal dUTP nick-end labeling-positive cells in tumor tissue were significantly higher in the T-50, T-60 and T-70 groups than those in the NT group. The Ki-67-positive areas were significantly decreased in the T-70 group compared with those in the NT and T-60 groups. Our data indicate that HTH at 60 and 70°C suppresses tumor growth in a glioma rat model. In particular, cell proliferation was significantly suppressed by HTH at 70°C. However, differences in the mechanism of action of HTH at 60 and 70°C were observed.
Keywords: Ki-67; apoptosis; glioma; high-temperature hyperthermia.