Enhanced effect of combined hyperthermia and chemotherapy (bleomycin, BCNU) in a neurogenic rat tumour (BT4A) in vivo.

The neurogenic rat tumour BT4A was serially transplanted to the dorsum of the right hind leg of BD IX rats. The tumours were treated with water bath heating at 44.0 degrees C for one hour alone or combined with bleomycin or BCNU, both given intraperitoneally at a dose of 20 mg/kg. Bleomycin alone had no effect on tumour growth. Hyperthermia or BCNU alone both caused a transient growth delay before regrowth. Combination of hyperthermia and bleomycin caused a significantly enhanced effect with 8 partial regressions in 9 tumours. BCNU and hyperthermia resulted in 9 complete and one partial regressions of 10 treated tumours. Eight of these were cured. We conclude that the antitumour effects as well as the side effects caused by the combination of local hyperthermia and systemic administration of BCNU and bleomycin deserve further investigation.