Inhibition of DMBA-induced carcinogenesis by phenformin in the mammary gland of rats

It is shown that daily oral administration of 5--10 mg of an antidiabetic biguanide-phenformin (phenethyl-biguanide) for 2.5--5 months suppressed DMBA-induced mammary tumour development in rats considerably. Phenformin-treated rats revealed-a tendency towards a decrease in blood Insulin level (radioimmunoassay). The obtained data are regarded as additional evidence for the proposed existence of the same metabolic background of diseases of compensation, i.e. adult-onset diabetes, artherosclerosis and Cancer, and suggest studies on possible antitumour effect of phenformin in man.