The Role of Estrogen in Breast Cancer

Estrogen is a hormone that plays a vital role in women's health, including breast and bone health. Let's learn about the role estrogen plays in women's health and how suppression of this hormone lowers the risk of breast cancer recurrence in certain women.

Estrogen is a hormone produced by a woman's ovaries until she reaches menopause. At menopause, defined as 12 months after a woman's last menstrual cycle, the ovaries stop making estrogen. This estrogen deficiency is what causes many symptoms of menopause, like hot flashes and vaginal dryness.

Illustration of human oestrogen receptor
Laguna Design / Oxford Scientific / Getty Images

What Is Estrogen Therapy?

Some women take hormone therapy, usually prescribed during perimenopause or early menopause, to alleviate distressing menopausal symptoms, especially hot flashes. Hormone therapy can contain both estrogen and progesterone, or just estrogen.

If a woman does not have a uterus—for instance, if she had a hysterectomy—then she may just take estrogen therapy alone. If a woman has a uterus, she needs to take progesterone in addition to estrogen. This is because estrogen therapy may lead to thickening of the lining of the uterus, which could cause endometrial cancer. Adding progesterone counteracts these effects.

It's important to know that, according to the U.S. Federal Drug Administration (FDA), hormone therapy is contraindicated in any woman with current breast cancer, a history of breast cancer, or suspected breast cancer.

How Estrogen Is Related to Breast Cancer

According to the American Cancer Society, approximately two out of three breast cancers are hormone receptor-positive. This means that the cancer cells have receptors for either or both of the hormones estrogen and progesterone.

Estrogen stimulates the growth of breast cancers that are estrogen receptor-positive. This is why menopausal hormone therapy is contraindicated in women with breast cancer or a history of breast cancer, so as to not increase a woman's risk of breast cancer recurrence.

Estrogen Suppression Therapy

Most types of hormone therapy for breast cancer, like selective estrogen-receptor modulators or aromatase inhibitors, either lower estrogen levels or stop estrogen from acting on breast cancer cells. This kind of treatment is helpful for hormone receptor-positive breast cancers, but it does not help patients whose tumors are hormone receptor negative (both estrogen-receptor and progesterone-receptor-negative).

Estrogen Linked to Bone Health

A healthy level of estrogen in your body builds and maintains strong bones. However, if you've had chemotherapy or if you're taking estrogen-suppression medication after treatment for breast cancer, your estrogen levels will be low. Guard your bone health by understanding how estrogen affects your bones.

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4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. The 2017 hormone therapy position statement of The North American Menopause Society. Menopause. 2017;24(7):728-753. doi:10.1097/GME.0000000000000921

  2. U.S. Food and Drug Administration. Menopause: Medicines to Help You. Updated August 22, 2019.

  3. American Cancer Society. Breast Cancer Hormone Receptor Status. Updated September 20, 2019.

  4. American Cancer Society. Hormone Therapy for Breast Cancer. Updated September 18, 2019.