A combination treatment by local anethetics, heat and radiation will be performed on HeLa cells, several human tumor cell lines, as well as on normal fibroblast cell lines. The aim is to observe potentiation of radiation lethality by heat and anesthetics, where the effect of the potentiating agents administered by themselves has a minimum adverse effect in the test systems used, with the colony forming ability taken as the end point. Comparisons will be made of the radiopotentiating ability of heat and anesthetics in the different cell lines, and conditions will then be sought, whereby neoplastic cells are affected in preference to cells of normal tissue origin. Treatment times not to exceed 6 hours will be used; synchronous cultures of HeLa cells will be used to establish that radiopotentiation can be obtained in homogenous populations. Repair of potentially lethal radiation damage will be followed in confluent cultures of cells from tumor and normal lines, where repair is registered as an increase in colony forming ability of cells in function of time postirradiation before dispersion and plating. The effect of heat, local anethetics (poraine, lidocaine, tetracaine, chlorpromazine) and polyamines alone or in combination, on the repair of radiation damage, will be investigated. A feasibility study of the use of biopsy material from human tumors for radiopotentiation by heat and local anesthetics will be conducted. The soft agar method currently used for chemotherapeutic screening will be adapted for this study.