Physiological bases of breast cancer prevention.

The relevance of this work lies in the possibility of extrapolating conclusions drawn here to the human situation, since we have assessed the validity of the rat model for the study of breast cancer in women through comparative studies in these two species (Russo and Russo, 1988). The novelty of our studies is the evidence that hCG protects the mammary gland against carcinogenic initiation and progression, mimicking the physiological process of pregnancy, without crippling other reproductive or endocrine functions (Russo et al, 1990d; Russo and Russo, 1992). The importance of both differentiation and cell proliferation in tumour initiation and progression, which we have stressed in previous publications (Russo and Russo, 1980, 1987, 1988; Russo et al, 1982) validates the use of these end-points for assessing the effect of hormones under the influence of hCG on the mammary gland initiated in the process of carcinogenesis. Collectively, our results provide solid bases for developing physiological means of breast cancer prevention and control.