• 1 January 1979
    • journal article
    • research article
    • Vol. 39  (8) , 3248-3253
Abstract
The effect of hyperthermia on normal and tumor tissue was studied following water bath heating of a methylcholanthrene-induced fibrosarcoma (FSaI) isotransplanted into the feet of C3H mice. The time-temperature relation for the 50% tumor control dose over the temperature range of 41.5-45.5.degree. C showed a log linear relationship which followed a biphasically modified Arrhenius plot. At temperatures above 43.degree. C, there was a 50% reduction in heating time to obtain the 50% tumor control dose for each 1.degree. increase in temperature, corresponding to an activation energy of 140 kcal/mol. At temperatures below 43.degree. C, the curve was steeper, with a tendency to double the treatment time for each 0.5.degree. reduction in temperature (activation energy, approximately 230 kcal/mol). Normal tissue damage in the tumor-bearing foot was estimated at 2 levels with a 50% response dose assay. Severe normal tissue damage showed a time-temperature relationship similar to the tumor response, thus indicating no variation in therapeutic ratio at different temperatures. For slight tissue damage, the therapeutic ratio increased with decreasing temperatures, yielding a better therapeutic ratio at lower temperatures. The time-temperature relationship obtained in the FSaI fibrosarcoma is supported by other studies and points to a general time-temperature relationship for hyperthermic tumor destruction.

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