Increased cures using fractionated exposures of x irradiation and hyperthermia in the local treatment of the Ridgway osteogenic sarcoma in mice

Experiments were carried out to determine the effect of heat and/or x rays on the Ridgway osteogenic sarcoma in AKD₂F₁/J male mice. Tumors averaging 0.9 ± 0.2 cm in diameter were exposed to 200 rads and/or heat three times on alternate days. Tumor core temperatures of 42.5 ± 0.5°C were maintained for 15, 30 or 45 min immediately before or after X irradiation. Heat alone did not effect cures whereas radiation alone cured 8 of 18 animals (44%). In contrast, 71 of the 74 animals (96%) receiving the combined treatment were cured. Radiation was equally effective whether given immediately before or after tumor hyperthermia. There were no differences in cure rates in the 15, 30 or 45 min heat/radiation groups.