The first simultaneous intraoperative hyperthermia and radiotherapy procedure: Dog experiment and technique

The Department of Radiation Therapy of Howard University Hospital was the first to revive (1976) the use of intraoperative radiotherapy, or direct view irradiation, using electron beam (IORTe^-) in the United States. Since that time, this pioneering effort has gained both national and international acceptance. Now, many leading centers employ this investigational treatment modality. Recently, a new mode of cancer therapy has been gaining acceptance, namely hyperthermia (the treatment of cancer by heat). Hyperthermia has been shown, both experimentally and clinically, to improve the rate of local control (thermal enchancement ratio [TER]) when combined with radiation therapy in the treatment of cancer. Maximal TER has been observed with simultaneous or immediate application of radiation and hyperthermia for both tumor and normal tissues. Therefore, to achieve maximum therapeutic gain, selective, intraoperative, simultaneous heating and irradiation of the tumor with mechanical retraction of the normal and sensitive structures from the treatment field seems a promising alternative. There have been no published reports, to the authors's knowledge, on the combination of simultaneous IORTe^- with intraoperative hyperthermia (IOHT). To employ this combination in human subjects, several questions must be answered first using animal models, including the technical and practical feasibility, the toxicity and morbidity, as well as the pathologic changes that may arise. The technical aspects of the first animal case, using a mongrel dog, applying simultaneous IORTe^- and IOHT are presented.