EVALUATION OF 45-DEGREES-C HYPERTHERMIA AND IRRADIATION .2. A PHASE-1CLINICAL-TRIAL IN HUMANS BY THE RADIATION-THERAPY-ONCOLOGY-GROUP

This report describes the experience in 40 evaluable patients entered into a Radiation Therapy Oncology Group (RTOG) study to evaluate the f easibility of administering 45-degrees-C for 15 minutes for superficia l malignant lesions: 18 patients (45%) tolerated only 1 heat session a t 45-degrees-C; 7 (17.5%), 2 sessions; 4 (10%), 3 sessions; and 3 (7.5 %) tolerated greater-than-or-equal-to 4 sessions. The overriding reaso n for discontinuing a 45-degrees-C treatment was pain. Of the 40 evalu able patients, 22 (55%) had complete tumor regression, and 8 (20%) had partial regression. Tumors less-than-or-equal-to 3 cm in diameter had significantly better complete tumor response than lesions > 3 cm (85% vs 41%) (p = .02). We conclude that 45-degrees-C heating is difficult to use in patients chiefly because of pain; this may be due in part t o inadequacy of currently available external hyperthermia equipment. C aution must be exercised in the application of thermal isoeffect heat dose concepts in clinical practice until further trials have been perf ormed and a better understanding of the time-temperature relationship is established.