The effect of bleomycin and its combined effect with radiation on murine squamous carcinoma treated in vivo.

Many previous reports testify to the effectiveness of bleomycin as a drug for the clinical treatment of squamous carcinomata, and some radiotherapists have considered the possibility that an improved therapeutic ratio might be obtained by combined treatment with bleomycin and radiation. This consideration has been stimulated by recent reports of the effects of combined treatment with bleomycin using mammalian cells in vitro. Experiments are described here in which a murine squamous carcinoma has been used to obtain a survival curve for cells of tumours treated in vivo with single doses of bleomycin alone or in combination with radiation given before or after the drug. The survival curve for drug alone was a multicomponent curve with D(0) values of 0·1, 0·75 and 2·7 mg/kg. However, the results of the experiments with combined treatment showed no evidence of potentiation.