OBJECTIVE: To develop optimal techniques for greater differentiation between tumor and normal tissue response to hyperthermia and radiation. APPROACH: Tumors, normal tissues, and cultured cells will be irradiated prior to exposures of variable temperatures. Fractionation studies of radiation alone and in combination with hyperthermia will be carried out to determine time-dose relationships of hyperthermia and ionizing radiation. Judicious combinations of temperature variations and irradiation may permit cures of tumors which appear to be relatively radioresistant and improve cure rates for tumors which are now considered radiocurable. Evaluations will be based on X-ray doses required to cure 50% of third-generation transplants of a C3H mouse mammary adenocarcinoma. Evaluations of skin response of treated mice will be done. In vitro experiments will be done with synchronized and asynchronous Chinese hamster ovary cells.