Androgens and the breast

Androgens have important physiological effects in women while at the same time they may be implicated in breast cancer pathologies. However, data on the effects of androgens on mammary epithelial proliferation and/or breast cancer incidence are not in full agreement. We performed a literature review evaluating current clinical, genetic and epidemiological data regarding the role of androgens in mammary growth and neoplasia. Epidemiological studies appear to have significant methodological limitations and thus provide inconclusive results. The study of molecular defects involving androgenic pathways in breast cancer is still in its infancy. Clinical and nonhuman primate studies suggest that androgens inhibit mammary epithelial proliferation and breast growth while conventional estrogen treatment suppresses endogenous androgens. Abundant clinical evidence suggests that androgens normally inhibit mammary epithelial proliferation and breast growth. Suppression of androgens using conventional estrogen treatment may thus enhance estrogenic breast stimulation and possibly breast cancer risk. Addition of testosterone to the usual hormone therapy regimen may diminish the estrogen/progestin increase in breast cancer risk but the impact of this combined use on mammary gland homeostasis still needs evaluation

Serial monogamy increases reproductive success in men but not in women

Evolutionary theory predicts that males seek more sexual partners than females because of their higher fitness benefits from such a reproductive strategy. Accordingly, variance in numbers of partners and offspring is expected to be greater and association between mating and reproductive success to be stronger in males. Studies testing key predictions of this hypothesis in humans are lacking. Using data of 3700 men and 4010 women living in contemporary United States, we examined sex differences in the variance of number of spouses and offspring and in the association between spouse number and number of offspring. The results suggested a stronger selective advantage of serial monogamy in men than in women. Variance in spouse and offspring number was, respectively, 5% and 10% higher in men. In addition, the association between mating and reproductive success was stronger in men, so that men with 3 or more consecutive spouses had 19% more children than men with only spouse, whereas spouse number beyond the first partner was not associated with number of children in women. When the sample was stratified by ethnic group, the sex differences were stronger among Black and Hispanic participants than among White participants. Copyright 2010, Oxford University Press.