How are estrogen receptors related to breast cancer treatment?

There are two genes that encode for two different estrogen receptors, alpha and beta. Oncology professor Robert Clarke, PhD, DSc, explains how estrogen receptors can affect a woman's breast cancer treatment.

Transcript

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ROBERT CLARKE: The estrogen receptor is present in many other tissues in the body. The estrogens control a whole series of different things

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at different times in development, really remarkable receptor protein that controls signaling.

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There are two genes that encode for two different estrogen receptors, alpha and beta.

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Estrogen receptor alpha is the one that's present in most breast cancers. That's the one that we think of when we target with tamoxifen,

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or letrozole and anti estrogen, or an aromatase inhibitor. And the estrogen receptor is present in many other tissues

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in the body. The estrogens control a whole series of different things at different times in development, really

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remarkable receptor protein that controls signaling.

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It's unique probably how it does it in breast cancer. It's a little different from how it functions in normal breast

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cells or in other cells in the body, which is why these drugs are often reasonably well tolerated.

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Whereas the big-gun cytotoxic drugs that people think of when they use chemo, as it were, target lots and lots of normal

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cells and have much-- often much more severe side effects. There are side effects with the endocrine treatments

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that we use. But some women tolerate them much better than they do chemotherapy.