THE TUMOUR-INHIBITING PROPERTIES OF 1·2 : 5·6 DIBENZANTHRACENE

¹ The Department of Pharmacology, University of Edinburgh

1. 1·2 : 5·6 dibenzanthracene in doses which are sublethal to normal rats greatly reduces the growth of tumours in rats (confirmation of Haddow).

2. Analysis of the growths of the tumour and the host shows that d.b.a. in the doses described inhibits the growth of the host more powerfully than the growth of the tumour.

3. Doses of d.b.a. sublethal to normal rats, although they decrease tumour growth, decrease rather than increase the expectation of life of tumour-bearing rats.

4. Injections of d. b. a. act more powerfully on tumours close to than on tumours farther away from the site of injection.

5. Rats dwarfed by previous injections of d.b.a. show a normal susceptibility to tumour inoculation.

6. The action of d.b.a. in inhibiting tumours is not influenced by administration of stradiol or by castration.

This work was made possible by a grant from the Medical Research Council for the maintenance of animals and laboratory expenses, and by a personal grant from the Cancer Control Organisation for South-East Scotland.

Thanks are also due to Dr. C. M. Scott for advice and assistance, and to Dr. A Haddow for supplying the Jensen rat sarcoma used in these experiments.