Identification of Estrogen Receptors and Their Role in Breast Cancer

摘要

The development of breast cancer has been linked to a variety of factors, including age, parity, family history and hormonal milieu. Estrogen, the female sex hormone, is a powerful mitogen and promotes neoplastic growth in mammary epithelium. In vitro, estrogens have been shown to modulate human breast cell via alpha and beta estrogen receptors (ER) (Zhou, Ng et al. 2000) While ERJ3 is preferentially expressed in normal breast tissue, ERa is abundantly expressed in invasive and in situ ductal carcinomas (Zhou, Ng et al. 2000). Tamoxifen, a non%steroidal anti-estrogenic drug is widely used for adjuvant therapy of breast cancer. ERa expression is currently the best method to predict if a cancer will respond to hormonal therapy. However, 35% of the primary tumors, which are ERa - positive do not respond to hormone therapy and about 10% of ERa-negative tumors are hormonally responsive (Jordan, Wolf et al. 1988). It would immensely beneficial to predict with a greater degree of accuracy how a breast tumor would respond to the treatment with tamoxifen, especially in the light of growing evidence of carcinogenic effects of tamoxifen (Fisher, Costantino et al. 1994; Phillips 2001).