Estrogen Receptor Alpha in Human Breast Cancer: Occurrence and Significance

  • Simak Ali
  • R. Charles Coombes
Article

Abstract

Estrogens have long been recognized as being important for stimulating the growth of a large proportion of breast cancers. Now it is recognized that estrogen action is mediated by two receptors, and the presence of estrogen receptor α (ERα)3 correlates with better prognosis and the likelihood of response to hormonal therapy. Over half of all breast cancers overexpress ERα and around 70% of these respond to anti-estrogen (for example tamoxifen) therapy. In addition, the presence of elevated levels of ERα in benign breast epithelium appears to indicate an increased risk of breast cancer, suggesting a role for ERα in breast cancer initiation, as well as progression. However, a proportion of ERα-positive tumors does not respond to endocrine therapy and the majority of those that do respond eventually become resistant. Most resistant tumors remain ERα-positive and frequently respond to alternative endocrine treatment, indicative of a continued role for ERα in breast cancer cell proliferation. The problem of resistance has resulted in the search for and the development of diverse hormonal therapies designed to inhibit ERα action, while research on the mechanisms which underlie resistance has shed light on the cellular mechanisms, other than ligand binding, which control ERα function.

breast cancer estrogen receptor endocrine therapies resistance 

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Copyright information

© Plenum Publishing Corporation 2000

Authors and Affiliations

  • Simak Ali
    • 1
  • R. Charles Coombes
    • 2
  1. 1.CRC Laboratories, Department of Cancer Medicine, MRC Cyclotron BuildingImperial College School of Medicine, Hammersmith HospitalLondon
  2. 2.CRC Laboratories, Department of Cancer Medicine, MRC Cyclotron BuildingImperial College School of Medicine, Hammersmith HospitalLondon

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