Effects of the Antifertility Drug Enovid in Five Strains of Mice, With Particular Regard to Carcinogenesis

Publisher Website
Google Scholar
Abstract
The antifertility drug, Enovid, was tested for possible carcinogenicity in female mice of 5 specially selected strains: BALB/c, C3H, C3HFB, A, and C57BL. The drug was fed at 3 dose levels: 5 µg Enovid/g food that did not prevent reproduction, 10 µg/g that prevented some females from reproducing, and 20 µg/g that prevented all females from reproducing. The results emphasized that inbred strains of mice differed in their response to Enovid. Enovid treatment reduced the gain in weight in all strains. It had no effect on lifespan in 1 strain, but in 2 strains lifespan was lengthened and in 2 shortened because of the effect on tumors or other lesions. Cervical and vaginal lesions showing invasion of the epithelium into the stroma with varying degrees of progression were observed but limited, with few exceptions, to the BALB/c females. They occurred in control and treated females of this strain but with a higher incidence and possibly further progression in the group treated with the highestdose of Enovid. None of these lesions were observed grossly as tumors, all being found on histologic examination, and none had extended to organs and tissues beyond the vaginal wall or showed any evidence of having metastasized. Enovid treatment at these dose levels did not increase the occurrence of ovarian tumors, even in the highly susceptible strains C3H and C3HFB, or of mammary gland tumors in any strain. In fact, in the highly susceptible strain C3H mammary tumors were somewhat inhibited in the treated females. In strain C3HfB there was some inhibition of hepatomas by the treatment, probably related to the reduction in growth rate, and in BALB/c some inhibition of adrenocortical adenomas. Chromophobe adenomas of the hypophysis were significantly increased in old C57BL females treated with the highest dose of Enovid. Many of these were active in stimulating the mammary glands of these old females and caused the females to have to be necropsied. These results are discussed in the light of previous work on hormonally induced neoplasms in which usually relatively massive doses were given and of results of other tests for carcinogenicity of contraceptive drugs.

This publication has 0 references indexed in Scilit: