Effects of RP-170 and cepharanthin on hyperthermia and thermoradiotherapy of C3H/He N mouse NF sarcoma

Thermotolerance is induced by the first heating and reduces the effect of the second heating performed after a proper time interval, the mechanism of which should be solved for successful hyperthermic treatment of cancer. Interactions of drugs and hyperthermia have been studied to inhibit the induction of the thermotolerance, or to show thermoenhancement which makes thermotolerance meaningless. Thermosensitivity and thermoradiosensitivity of new hypoxic cell radiosensitizer RP-170 and Cepharanthin on C3H/He N mouse NF-sarcoma were examined using water bath method and 60Co-γ ray irradiation. The experiment started on the day when the tumors implanted in the right foot of the mice grew up to about 6 mm in a diameter on an average. Those responses were analyzed measuring tumor growth-curve and-time (TGF 50x7). TGT50x7 is the expression of the days in which the tumor volumes of 50% of the animals reach 7 times the value at the start of treatment. Remarkable thermoenhancement and thermoradioenhancement were revealed by the treatment combined with both RP-170 and Cepharanthin, although these drugs did not inhibit thermotolerance. It was suggested that hyperthermia and thermoradiotherapy with these drugs were useful in the cancer treatment. (author)