The oncogenic potential of a combination of hyperthermia and chemotherapy agents.

The modulating effect of 43 degrees C hyperthermia on the induction of oncogenic transformation by the antineoplastic agents, actinomycin D, mitomycin C, and 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) was examined using the C3H 10T1/2 cell line. For any given level of cytotoxicity, cells exposed to the three chemotherapy agents at 37 degrees C showed similar frequencies of transformation. Transformation frequencies induced by all three drugs were reduced by hyperthermia. The reduction was most pronounced for cells exposed to BCNU, and to a lesser extent, by cells exposed to actinomycin D and mitomycin C. The modulating effects of heat on drug-induced transformation incidence appeared to be independent of whether application of heat and drug was concurrent or sequential.