ABSTRACT
Vascular injury has been implicated as a major factor in the development of tissue damage after hyperthermia in the clinical range. Measurement of tumor blood flow in experimental animals and in man has given average perfusion rates which range from less than those of adjacent normal tissues to considerably more. Thermotolerance induced in experimental tumors is similar to that in normal tissues. In view of this, and of the variation between normal tissues, it may be advisable to give clinical treatments at intervals which allow the decay of thermotolerance. The importance of the microcirculation in the expression of thermal damage has also been demonstrated in tumors growing in transparent chambers implanted in the skin of the rat or cheek pouch of the hamster; hyperthermia caused failure of the microcirculation followed by tumor necrosis only in the regions showing circulatory failure. The pathological effects of hyperthermia in various normal tissues have been reviewed by Fajardo.
