INFLUENCE OF HYPERTHERMIA ON PROLIFERATION KINETICS OF MALIGNANT-TUMORS IN CHILDREN

Embryonal tumors (21 Wilms' tumors, 11 neuroblastomas, 9 rhabdomyosarcomas) and 16 sarcomas of the skeleton of childhood were studied with an autoradiographic in vitro method according to the responsibility to hyperthermia 42.5-degrees-C/120 min, to Cyclophosphamide, to Doxorubicin, and to Actinomycin D, and also to the combined application of hyperthermia and cytostatic drugs. Hyperthermia alone reduced the median H-3-thymidine, respect. H-3-uridine incorporation between 38.1 and 56.8%, respect. 45.9 and 63.9%. Hyperthermia inhibited the RNA synthesis stronger than the DNA synthesis. The combined application of hyperthermia and the different cytostatic agents increased the inhibition of incorporation of the labeled precursors extraordinarily (by Cyclophosphamide to 81.6-90.8%, by Doxorubicin to 60.8-80.0, by Actinomycin D to 79.4-93.2%). In case of the inhibition of H-3-thymidine or H-3-uridine incorporation lower than 40% (resistance), in each case the combination of hyperthermia and cytostatic drug overcomes the resistance. The consequences of hyperthermia sensitivity testing of solid tumors of human beings are discussed.