The influence of estrogen on cancer incidence and adrenal changes in ovariectomized mice on calorie restriction.

The occurrence of mammary carcinoma (1, 2, 3, 4) following ovariectomy in certain strains of mice and the delay of mammary carcinogenesis in such mice by calorie underfeeding seen in preliminary experiments (5) suggested the testing of the ef fects of exogenous estrogen administration, partic ularly in the calorie restricted animal, on cancer production. Studies were therefore made on fullfed and calorie restricted Ovariectomized mice, both with and without exogenous estrogen, observ ing effects upon the reproductive apparatus, the adrenal cortex, and upon mammary cancer inci dence. METHODS C3H strain mice were Ovariectomized at wean ing (21 to 23 days) and caged individually in a room held at 78°+ 4° F. and 45 ±10 per cent some instances the animals were sacrificed for morphologic study when a mammary tumor was noted and in other instances the tumor was re moved surgically under anesthesia and the mouse studied further as will be noted under results. The adrenal glands, the uteri, and the mammary tu mors were sectioned and studied microscopically. In the estrogen treated animals 0.5 j of diethylstilbestrol per day per mouse was administered in the food. RESULTS Table 1 presents a summary of the major find ings in the study. It will be seen that the diethylstilbestrol-treated C3H castrates on full feeding show a markedly lower average cancer age than their controls without estrogen. This occurs with a total suppression of adrenal adenomatous change