5 Hyperthermia in Cancer Therapy: Model Systems

Abstract

I. INTRODUCTION
Over the past two decades, a number of institutions have gained extensive clinical experience in the use of hyperthermia, particularly in conjunction with radiation therapy, in the treatment of human malignancies. Results have pointed consistently to the potential therapeutic benefit to be gained from the use of this combination therapy as compared with radiotherapy alone. In 1984, Overgaard reviewed the world’s literature and found a total of 213 published studies with nearly 11,000 patients having been treated (Overgaard 1985). Of particular interest were patients in whom two or more tumors of the same type were treated. In several studies of this type, involving several hundred patients, it was shown that the complete response rate for local hyperthermia combined with radiotherapy was roughly double that achieved with radiotherapy alone, i.e., approximately 60% versus 30%. More recently, randomized Phase III studies from pet dogs with oral squamous cell carcinomas (Gillette et al. 1987) and human patients with recurrent head and neck lesions (Valdagni et al. 1988) have shown that the same dose of radiotherapy plus heat yields a larger percentage of complete responses and long-term tumor controls than that achieved with radiotherapy alone. These results have been obtained without a significant increase in normal tissue complications. Thus, it is felt that hyperthermia holds a great deal of promise for improving control rates for tumors with high local or regional failure probability. Despite the optimism, however, there are a number of critical questions that still need to be addressed regarding treatment...