Studies on the promoting phase in the stages of carcinogenesis in mice, rats, rabbits, and guinea pigs.

Abstract

1. Turpentine, acridine, fluorene, phenanthrene, castor oil, ricinoleic acid, glyceryl monoricinoleate, oleic acid, and silver nitrate have been tested for tumor-promoting activity following a single application of 9,10-dimethyl-1,2-benzanthracene in the mouse. They were ineffective as promoters of tumors. 2. The effects of wound healing, turpentine and croton oil applications, following a single application of 9,10-dimethyl-1,2-benzanthracene, have been tested for tumor-promoting activity on the rabbit. Wound healing alone has been found to be an effective stimulus. 3. The effects of repeated applications of croton oil, following a minimal number of applications of 9,10-dimethyl-1,2-benzanthracene have been investigated in the guinea pig. No tumors were induced. 4. The effects of croton oil, following three applications of 9,10-dimethyl-1,2-benzanthracene in the rat, have been investigated. No tumors were induced. 5. The specific effect of croton oil on the mouse and of wound healing on the rabbit, as promoters of tumor formation are discussed.