ER protein, particularly the more widely studied ERa has varied associations in the specific hyperplasic and atypical in-situ lesions of the breast (2). Although these have yet to be linked in the way of predicting later BC risk in the decade after biopsy. However, this association of ERa and hyperplastic epithelial lesions promises to add to the estimation of both BC risk, and perhaps in indicating responsiveness to hormonal elements in the prevention setting (3). Estrogen, mediated through the ERa, has a central role in normal growth and development of the breast (4) as well as a well-developed and proven role in the evaluation of established neoplastic disease (5). Cell proliferation involving E is also central to the expression of other genes, including most prominently, progesterone receptor
(PR) (6). PR mediates the mitogenic effect ofprogesterone which further stimulates proliferation (4). This latter effect has now been demonstrated epidemiologically in that hormone replacement therapy (HRT) after menopause has only a mild effect on BC risk if it involves estrogen only (7), whereas the addition of progestins adds significantly to the likelihood of later BC development in the post-menopausal woman (8-10)
Most ofthe studies of expression in normal ducts and lobules, as well as in-situ neoplasia, are immunohistochemical studies focused on the ERa, although the potential cross reactivity for the much more recently discovered is not currently clear (11). Normal terminal duct-lobular units express ERa approximately 90% ofthe time, and in perhaps a third ofthese the expression is quite limited and only seen in a minority of cells. During the childbearing years (12), the number of positive cells varies with the menstrual cycle and is much higher during the follicular phase. Proliferation however peaks during the luteal phase (13), suggesting that the mitogenic effect of estrogen is either delayed or indirect, and mediated by other interactions, probably mostly with progesterone (14, 15) and prolactin. In post-menopausal women, the expression of ERa is relatively high (2) and stable in the absence of HRT.
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Are Menopause Symptoms Playing Havoc With Your Health and Relationships? Are you tired of the mood swings, dryness, hair loss and wrinkles that come with the change of life? Do you want to do something about it but are wary of taking the estrogen or antidepressants usually prescribed for menopause symptoms?