Clinical evaluation of thermoradiotherapy for deep-seated tumors

Between October 1981 and February 1985, RF capacitive heating with frequencies of 8 and 13.56 MHz was combined with radiotherapy in the treatment of 28 deep-seated tumors that were previously considered incurable by conventional radiotherapy alone. Intratumor temperatures of higher than 42 deg C were achieved in 69 % of overall heat sessions. Clinical evaluation was made by calculating the percentage of tumor regression from pre- and post-treatment CT films. As for the criteria of clinical evaluation, complete regression (CR) was defined as clinical disappearance of any measurable tumor, partial regression a and b (PRa and PRb) as regressions of 80 % or more and 50 to less than 80 %, respectively, and no response (NR) as less than 50 % regression. Of 28 deep-seated tumors, 4 (14 %) achieved CR, 5 (18 %) PRa, 11 (39 %) PRb and 8 (29 %) NR. In some NR and PRb tumors, however, CT scan revealed remarkable increases in low density areas that suggested necrosis of tumor tissues. This was proved by subsequent histological examination. Clinical tumor response appeared to decrease as the initial size of the tumor increased and to be independent of any TDF factor for radiotherapy and the number of heat sessions. (author)