Suppression of Mammary Tumorigenesis in C3H/He Mice by Ovariectomy or Treatment With 2-Bromo- α -ergocryptine: A Comparison 2

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Abstract
We compared the effects of chronic treatment with 2-Br-α-ergocryptine (CB-154) and of ovariectomy on the genesis of mammary hyperplastic nodules (HN) and mammary tumors in the C3H/He mouse. CB-154 is an established potent suppressor of pituitary prolactin. Eighty-five 21- to 25-day-old female mice were divided into three groups. Group I received daily sc injections of 0.1 mg CB-154. Group II was ovariectomized and group III served as controls. Mice were examined weekly for mammary tumors. Fifteen months from onset of treatment all surviving mice were killed. The mean number of HN per inguinal mammary gland, total number of mammary tumors, and number (percent) of mice with mammary tumors in each group were, respectively: controls—4.6±1.1, 41, 24/29 (83%); ovariectomized—1.2±0.6, 20, 14/28 (50%); and CB-154-treated—0.2±0.1, 16, 13/28 (46%). A significant (P<0.001) and equally comparable inhibition of mammary tumor incidence was observed in the ovariectomized and CB-154-treated mice. Thus early ovariectomy and CB-154 treatment (specific inhibition of prolactin secretion) appeared equally effective in the prophylaxis of mammary tumorigenesis in the C3H/He female mouse.