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Hormone-Driven Breast Cancer

Posted Aug 24 2008 1:49pm
ANNOUNCER: When a woman is diagnosed with breast cancer, one of the first things physicians want to determine is the effect that estrogen has on the cancer. Although estrogen plays many vital roles in a woman's body, in nearly two-thirds of breast cancers, it can also stimulate cancer growth, making the determination of the cancer's estrogen receptor status crucial.

KIMBERLY BLACKWELL, MD: Estrogen receptor status really refers to whether or not a cancer cell has the estrogen receptor on it.

Estrogen is just a protein that's found in the female body. The way they interact is that estrogen would be circulating in the bloodstream, and when it encounters its own receptor, it will bind to it. In breast cancer cells that have the estrogen receptor, otherwise known as estrogen receptor-positive, that leads to the growth of the breast cancer cells. So in a sense, the estrogen binds to the estrogen receptor and acts, in a sense, like food for the breast cancer cell. It stimulates it to grow.

Estrogen receptor-negative tumors do not possess the estrogen receptor, which is simply a protein on their surface, and thus, we believe, do not depend on the female hormone estrogen for their growth.

ANNOUNCER: Another key hormone whose receptor status is important is progesterone, although its effect on cancer growth is not as well-defined.

MARY CIANFROCCA, MD: We do look for both estrogen and progesterone receptors in a patient's cancer. It's a little bit debatable right now whether that helps us in decision-making. There is some early evidence that patients do better if they're both estrogen and progesterone receptor-positive than if they're just estrogen receptor-positive and progesterone receptor-negative. So we do routinely test for both receptors in all patients' cancers.

ANNOUNCER: Estrogen and progesterone receptor status is usually determined at the time of diagnosis by performing a biopsy of a woman's breast cancer. These tests are highly accurate and give physicians an indication that certain forms of treatment may be beneficial for the patient.

MARY CIANFROCCA, MD: Once estrogen receptor status is known, decisions are made as to whether a patient can benefit from hormonal therapy. If a patient's estrogen receptor-positive, they have the potential to benefit from hormonal therapy, where if they're hormone receptor-negative, they don't have the potential to benefit from that type of therapy.

ANNOUNCER: Hormonal therapy removes the effect of estrogen, so breast cancer cells are not stimulated to grow. If a woman's breast cancer is in the early stages and is estrogen receptor-positive, there are a number of strategies that doctors use to reduce the amount of estrogen in a woman's body.

KIMBERLY BLACKWELL, MD: The first strategy is to remove the estrogen, and you can do that a number of ways. In young woman, who have not yet gone through menopause, you can remove their ovaries, or there are shots that will shut down the ovaries in young women. So that's simply removing the estrogen from a woman's body, and that's been shown to be a very effective strategy in treating breast cancer.

Another way of not quite removing but reducing the amount of estrogen in a woman's body — and in this case, a woman who's already gone through menopause — is a class of drugs known as aromatase inhibitors. There are three approved aromatase inhibitors in the United States: letrozole (which is also known as Femara), anastrazole (which is also known is Arimidex), and exemestane (which is also known as Aromasin).

And although they each work a little bit differently, the net effect of these drugs is that they're a pill taken once a day that reduce the amount of estrogen that's made in a woman's body.

The second strategy to using hormonal status in the treatment of breast cancer is simply to block the estrogen receptor. In the United States, there are two drugs that are FDA-approved to do this. One drug is an older drug known as tamoxifen, that has been used in hundreds of thousands of woman to prevent their breast cancer from coming back, and it simply works by blocking the estrogen from getting to the estrogen receptor.

And there's a newer drug, which is known as fulvestrant (or Faslodex is its trade name), and this is a shot given once a month, and it works very similar to tamoxifen in that it blocks the estrogen from getting to the estrogen receptor. So the good news in all this is that in a woman whose tumor is estrogen receptor-positive, we now have at least five or six different therapies.

ANNOUNCER: Additionally, chemotherapy is sometimes added to hormonal therapy in women who are diagnosed with estrogen receptor-positive metastatic breast cancer, where the cancer has spread beyond the breast, or women who are diagnosed with early stage disease and are at high risk of recurrence.

For women whose tumors are estrogen receptor negative, chemotherapy alone is recommended.

MARY CIANFROCCA, MD: Generally, patients who are estrogen receptor-negative are limited primarily to chemotherapy, since they won't benefit from hormonal therapy, because they don't have the proper receptors on their cancer cells.

Common chemotherapy drugs that are used in breast cancer are the anthracyclines, of which the most commonly used is Adriamycin, and also the taxanes, which the most commonly used are paclitaxel and docetaxel. ANNOUNCER: Determining the estrogen and progesterone receptor status of a breast cancer is an important step in defining the characteristics of a woman's individual cancer and starting her on the treatment regimen that will most effectively fight her cancer.

KIMBERLY BLACKWELL, MD: When a woman's diagnosed with a breast cancer, // She should formulate a list of questions that she can ask her physician, and this list of questions should include questions like, "Does my breast cancer have the estrogen receptor?" Are these the drugs that have been shown to work best in estrogen receptor tumors? Are these the chemotherapy drugs that have been shown to work best in estrogen receptor negative tumors?"

And finally, she should ask some very frank questions about why her doctor has chosen to use one hormonal drug over another in her therapy, and she should also ask why her doctor is choosing the chemotherapy drugs that he's choosing.

The good news in breast cancer is there is a number of treatment options. It's not one size fits all anymore. And so a woman should know the features of her breast cancer and how her doctor has used those features to determine what kind of treatment she will get to prevent her breast cancer from coming back.

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