Response of mouse sarcoma-180 to bleomycin in combination with radiation and hyperthermia.

The response of a transplantable mouse tumor, S-180, grown intradermally in inbred Balb/c mice, to bleomycin (BLM), irradiation (RT) and hyperthermia (HT) was studied by observing tumor growth changes up to 120 days after treatment. BLM, at 20 mg/kg body weight, and 10 Gy gamma radiation individually produced identical tumor cure, while hyperthermia at 42 degrees C, 60' or 43 degrees C, 30' resulted in a higher tumor response. Treatment with 43 degrees C, 30' after BLM was more effective than hyperthermia after radiation in effecting tumor cure as well as in inducing regrowth delay. In the drug +HT combination the low drug dose was almost equal in effect as the higher drug dose when followed by 43 degrees C, 30'. Combining the three modalities resulted in 100% tumor cure without any local recurrence during the observation period. The micronucleus study 24 h after treatment indicated enhanced cytogenetic damage by the combination treatments.