Breast Cancer - Arab Medical Association Against Cancer

Hormonal treatment 188HORMONAL THERAPYAn ovarian link that controls the growth of some breast cancers has been known for almost a century. Thediscovery of steroid receptors in the mid-1970s, however, has provided the rationale for a more selectiveapplication of endocrine treatment. Commonly, endocrine manipulations need a delay of 7 to 8 weeksbefore exerting their beneficial effects. So, all rapidly growing lesions are better treated with other formsof therapy.I. Physiological and Biological BackgroundThe hormonal environment of the breast is largely dependent on that part of the endocrine involving thehypothalamus, the pituitary gland and the ovaries (Fig. 13.3).Figure 13.3.Overview of the neuroendocrine control of breast development and function with relationship to gonadotropic hormones of theanterior pituitary and ovary.Estrogen is the major stimulus for the growth of hormone-dependent breast cancer, and most forms ofendocrine therapy are directed toward inhibiting, ablating, or interfering with estrogen activity.The ovaryis the principal site of estrogen synthesis, but it is also synthesized by the adrenal gland, adipose tissue,and even by mammary tumors themselves.After menopause, estrogens are essentially secreted by the adrenals. They are biosynthesized fromcholesterol with a series of enzymatic steps including cleavage, hydroxylation, and aromatization. Ductal