Breast Cancer Research and Treatment

, Volume 22, Issue 1, pp 91–100

Tamoxifen reduces serum insulin-like growth factor I (IGF-I)

  • Michael N. Pollak
  • Hung The Huynh
  • Susan Pratt Lefebvre
Article

DOI: 10.1007/BF01833337

Cite this article as:
Pollak, M.N., Huynh, H.T. & Lefebvre, S.P. Breast Cancer Res Tr (1992) 22: 91. doi:10.1007/BF01833337

Summary

Antiestrogens are widely used in the management of hormonally responsive breast cancer in both adjuvant and palliative settings, and are currently being evaluated as chemopreventive agents. The classical mechanism of action of these drugs involves inhibition of estrogen-stimulated neoplastic cell proliferation by blockade of estrogen receptors present on breast cancer cells. This paper reviews recent clinical and laboratory data that suggest that the commonly used antiestrogen tamoxifen also acts to reduce serum IGF-I levels. Estrogens appear to play a permissive role in growth hormone (GH) release by the pituitary gland and GH is known to stimulate IGF-I expression by hepatocytes. It is therefore possible that blockade of estrogen receptors in the hypothalamic-pituitary axis by tamoxifen interferes with GH release, leading to reduced hepatic IGF-I expression. In view of results suggesting that IGF-I is a more potent mitogen than estradiol for breast cancer cells and data demonstrating a positive correlation between estrogen receptor level and IGF-I receptor level of breast cancer cells, the IGF-I lowering effect of tamoxifen may contribute to the cytostatic activity of the drug. The interrelationships between steroid hormone physiology and IGF-I physiology may have relevance to a variety of commonly used treatments for hormonally responsive cancers.

Key words

breast neoplasmsinsulin-like growth factor Iprolactinsomatostatinsomatotropintamoxifen

Copyright information

© Kluwer Academic Publishers 1992

Authors and Affiliations

  • Michael N. Pollak
    • 1
  • Hung The Huynh
    • 1
  • Susan Pratt Lefebvre
    • 1
  1. 1.McGill University and Lady Davis Research Institute of the Jewish General HospitalMontrealCanada