Use of whole body hyperthermia as a method to heat inaccessible tumours uniformly: a phase III trial in canine brain masses

In this study, whole body hyperthermia (WBH) was assessed as a means of hea ting intracranial tumours uniformly. Twenty-five dogs received radiation th erapy and 20 the combination of radiation and WBH. Total radiation dose was randomly assigned and was either 44, 48, 52, 56 or 60 Gy. Because of WBH t oxicity, intercurrent disease or tumour progression, seven of the 45 dogs r eceived less than the prescribed radiation dose. For WBH, the target rectal temperature was 42 degrees C for 2 h and three treatments were planned. In five of the 20 dogs randomized to receive WBH, only one WBH treatment was given because of toxicity. WBH toxicity was severe in six dogs, and resulte d in death or interruption in treatment. Most tumours did not undergo a com plete response, making it impossible to differentiate tumour recurrence fro m brain necrosis as a cause of progressive neuropathy. Therefore, survival was the major study endpoint. There was no survival difference between grou ps. One-year survival probability (95% CI) for dogs receiving radiation the rapy alone was 0.44 (0.25, 0.63) versus 0.40 (0.19, 0.63) for dogs receivin g radiation and WBH. There was no difference in the incidence of brain necr osis in the two treatment groups. Results suggest that use of WBH alone to increase the temperature of intracranial tumours as a means to improve radi ation therapy outcome is not a successful strategy.