The induction of mammary cancer in rats

Abstract

1. The forced feeding of oil solutions of 7,12-dimethylbenz(a)anthracene (DMBA) to female rats of Sprague-Dawley or Wistar strains induced multiple mammary tumours in 4 to 6 weeks. The same treatment does not induce mammary cancer in rats of the Marshall strain and only after longer periods in rats of the August strain. 2. Intraperitoneal injection of the same hydrocarbon does not induce the mammary tumours. 3. Oral administration of DMBA or naphthalene increases ascorbic acid excretion of rats to a greater extent in Sprague-Dawley and Chester Beatty strain rats than in Marshall strain rats. 4. The induction of mammary cancer by DMBA was partially neutralised by feeding thymine or uracil. 5. Administration of DMBA reduced the growth of female Chester Beatty strain rats maintained on a 20 per cent protein diet if treatment started when the rats were 50 days. The growth inhibition was less if treatment started at 30 days, or if the rats were maintained on the stock rat cake diet. © 1962, The British Empire Cancer Campaign for Research. All rights reserved.