[Experimental study of hyperthermo-chemo-radiotherapy on transformed cells].

The combined effects of hyperthermia, chemotherapy with bleomycin and irradiation (hyperthermo-chemo-radiotherapy) on the growth of transformed cells, spontaneously established from Chinese hamster fibroblasts, were studied in vitro. Concomitant application of the 3 modalities with hyperthermia at 42 degrees C for 30 minutes, treatment with 0.02 microgram/ml of bleomycin for 60 minutes and 2-Gy irradiation led to the best effect with an 89% cytotoxicity, compared with those in cells treated with a single modality or 2 modalities. To determine the role of hyperthermia and irradiation in this enhanced cytotoxicity, the response of the cells to each modality was compared between hypoxic cells in the inner layer and aerobic cells in the outer layer of multicellular tumor spheroids. The hypoxic cells were very sensitive to hyperthermia and also the aerobic cells were very sensitive to irradiation, which appeared to be one of the mechanisms for the enhanced effects obtained with these 2 modalities.