Combination of hyperthermia and methotrexate in the treatment of transplanted Walker sarcoma

The purpose of this experimental study was to evaluate the possible synergistic effect of hyperthermia (HPT) and methotrexate (MTX) in Wistar rats transplanted with Walker sarcoma. HPT was induced by microwaves of 432 MHZ frequency transmitted through a source of 2 x 5.5 cm2 surface. The temperature in the tumor was maintained at 43 degrees C which was controlled by an intratumor thermocouple connected with an electronic thermometer. Three experiments were performed. First, in 5 rats HPT only was applied and one rat was used as control. Second, HPT and MTX in combination were given to 6 rats. Third, MTX alone was given to 6 rats. In the first experiment all 5 rats had 50% reduction of their tumors compared to control. In the second experiment complete disappearance of the tumor was noticed and in the third experiment the tumor increased in size. Histologically, in the responding tumors extensive necrosis was seen with thrombosed vessels. We conclude that HPT and MTX are synergistic in treating Walker sarcoma in Wistar rats.