Inducibility of microsomal enzymes in normal and pre-cancerous lung tissue. Synergistic action of 5-6 benzoflavon or methyl-cholanthrene in radiation induced carcinogenesis.

The inducibility of pulmonary microsomal enzymes and the biological effects of chronic induction by 5-6 benzoflavone and methylcholanthrene were compared in normal and precancerous rats. Two important points were shown out: a dose of 6000 WLM resulted in a permanent modification of the pulmonary microsomal enzymatic pool and 5-6 benzoflavon was a strong co-factor of radiation induced carcinogenesis. This synergistic action was demonstrated by a much shorter latency, moreover neo-formed tissue and epidermoid cancers with a particular morphology were observed. In all the cases cancers appeared within 100 days following the beginning of the chemical treatment.