Cancer of the Uterine Cervix in Mice Fed a Liquid Diet Containing an Antifertility Drug

A series of preliminary short-term experiments demonstrated: 1) Mice could be maintained on a liquid diet; 2) Enovid given to newborn BALB/c mice produced results similar to the effects of diethylstilbestrol; and 3) Enovid could be administered in a liquid diet to mice and produce changes in the endometrium similar to an estrogen effect. A long-term experiment was then begun, and BALB/c mice were given Enovid in Metrecal continuously. All 6 mice receiving the mixture for 518–721 days and 2 mice born to a mother on Enovid and continued on Enovid for 599 days had lesions of the uterine cervix, diagnosed as early cancer or infiltrating cancer. None of the mice on Metrecal alone developed cervical lesions. Previous reports on the induction of carcinoma of the cervix in mice by estrogens are reviewed, and the histology of the lesions induced by Enovid is described. The need for further studies is discussed.