TAMOXIFEN AND BREAST CANCER: HOW DOES TAMOXIFEN WORK?

Many questions relating to how tamoxifen inhibits the growth of breast cancer cells remain unanswered. For years tamoxifen was assumed to act simply by blocking the effects of estrogen on breast cancer cells (14). It is recognized that some types of breast cancer cells contain proteins called estrogen receptors. When estrogen, which normally is synthesized in the ovaries and carried by the bloodstream, comes in contact with cells carrying these estrogen receptors, the estrogen binds with the receptors in a way that triggers the growth of these cells. If estrogen can be removed from the system (for example, when the ovaries are removed), then these receptor-positive cancer cells are no longer stimulated to grow. Furthermore, if drugs can be given that interact with the estrogen receptors without stimulating cell growth, then the cell is blocked from the growth-triggering effect of estrogen even in the presence of estrogen. Although a variety of other mechanisms are currently under investigation, it appears that the mechanism by which tamoxifen inhibits breast cancer growth is at least in part related to its binding and blocking of the estrogen receptor.

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Cancer