Equipment for local hyperthermia therapy of cancer.

Technology for local heat therapy of cancer is evolving rapidly at a number of technologically diverse and geographically scattered institutions and companies. No single technology is superior to others in all applications, and no single company, laboratory, or research group has all the answers. An ideal system would provide focused heating at depth in a predictable fashion, with little probability of generating undesired hot spots in normal tissues and little interference with monitoring equipment. Existing systems approximate this ideal to different degrees, depending on the anatomy and geometry of the tumor and its surrounding tissues. In the foregoing discussion the important problem of measuring temperatures in tumors and normal tissues has been slighted. At the present time, all thermometry is necessarily invasive, and there are limitations to the number of points at which temperatures can be measured utilizing percutaneously placed catheters as conduits for thermometers. However, further advances in the art, the science, and the technology of local heat therapy are likely to be forthcoming in the next few years from a diverse community of investigators and young companies who are following an interesting variety of approaches. Continued research and development in the spirit of constructive, rather than destructive, competition will certainly advance the field substantially--much to the benefit of patients. At present, however, clinical engineers should realize that hyperthermia therapy for cancer is still experimental. Despite the flurry of commercial activity, considerable caution should be exercised in the purchase and use of hyperthermia equipment.