Hyperthermia in cancer therapy.

Many malignant cell lines exhibit a therapeutic response to supernormal temperatures. Selective destruction of tumor cells has been observed following moderate hyperthermia (42 degrees to 43 degrees C) in vivo, and tumor eradication by heat has been achieved without normal tissue morbidity. Thermal cell killing appears to be independent of oxygen tension, and the sensitivity of S-phase cells to thermal damage is complementary to that for cellular radiation response. Hyperthermia is therefore a promising adjunct to radiotherapy. At the Claire Zellerbach Saroni Tumor Institute, Mount Zion Hospital and Medical Center, San Francisco, the differential thermal sensitivity of malignant cells is being studied to achieve improved tumor control in patients refractory to more conventional treatments. Preliminary results of a two-year clinical trial indicated increased local objective responses when hyperthermia and radiation were used in combination.