[Study of blood flow in hyperthermia using human renal cell carcinoma heterotransplanted in nude mice--differences in histological tumour pattern upon the effects of hyperthermia]

Abstract

Utilizing two types of human renal cell carcinoma heterotransplanted in nude mice (JRC 1; papillary, avascular pattern, grade III, JRC 11; anaplastic and alveolar, hypervascular pattern, grade IV), we investigated the influence of tumor blood flow upon the effects of local hyperthermia (42.5 degrees C), induced by 915 MHz microwave. Blood flow was determined from the rate of thermal clearance by use of the bio-heat transfer equation. The rate of thermal clearance was measured at intervals of approximately 10 minutes throughout the treatment session after turning off the microwave for 50 seconds. With both strains it was necessary to increase the microwave power until the constant steady-state temperature of 42.5 degrees C was reached. The JRC 11 strain needed more power for the constant temperature than JRC 1, but it needed a greater decrease in power level during the heating session to maintain a constant steady-state temperature. This was an indication that the tumour blood flow decreased more markedly in the JRC 11 strain. In both tumours, a decrease of blood flow was observed during the heating session. In the case of the JRC 1 strain, it was observed that the mean value of blood flow was 1.87 times higher than that of JRC 11. This indicated a sharp reduction in blood flow in JRC 11 strain. This reduction was confirmed by the thermal clearance measurement at the end of the treatment session. A sharp reduction in blood flow in hypervascular tumour (JRC 11 strain) is caused by a stasis of intra-tumoural blood circulation during the heating.(ABSTRACT TRUNCATED AT 250 WORDS)