Effect of actinomycin D and neoarsphenamine on tumor control and skin tolerance in the rat.

Actinomycin D and neoarsphenamine were tested for their ability to produce therapeutically favorable radiosensitization in the WAG/Rij rat. Acute and late skin reactions and control of the BA1112 rhabdomyosarcoma were examined in drug-treated and untreated animals irradiated in single- and five-fraction schedules. Actinomycin D was found to protect skin and tumors when added 15 minutes before irradiation. Actinomycin D added 2 hours before irradiation in a five-fraction trial produced slight tumor sensitization accompanied by slight skin protection. Neoarsphenamine produced significant tumor sensitization without skin sensitization in one of the single-fraction trials, but had no effect in the five-fraction trials.