Clinical results after different protocols of combined local heat and radiation.

Since 1977, 69 patients with 138 multiple lesions have been treated with combined radiotherapy and hyperthermia, according to 3 protocols. Firstly, radiotherapy was given following a thrice-a-day fractionation scheme of 1.5 to 2 Gy/fraction, up to 60 Gy. Hyperthermia (42.5 degrees C/45 min) was applied each other day, immediately after the 2nd radiation fraction. Immediate response resulted significantly higher in the combined group (76% clearances in comparison with 46% after radiotherapy alone). Secondly, tumors received 40 Gy/8 fractions, twice a week, and hyperthermia (42.5 degrees C/45 min) was applied with each radiotherapy fraction, either immediately after irradiation (simultaneously) or 4 h later (sequentially). A remarkable improvement of radiation response was obtained, especially with the simultaneous treatment. Thirdly, tumors received 30 Gy/6 fractions, twice a week. Hyperthermia (45 degrees C/30 min) was applied simultaneously with each radiotherapy fraction and the surrounding skin was cooled. Complete tumor clearance was achieved in 88% lesions in comparison with 31% after radiotherapy alone. As expected, the incidence of thermal damage on uncooled skin was also increased. In conclusion, the best therapeutic ratio was obtained with low fractional radiotherapy doses and low temperature hyperthermia.