Hormonal Therapy

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Hormonal therapy medicines treat hormone-receptor-positive breast cancers in two ways:

  • by lowering the amount of the hormone estrogen in the body
  • by blocking the action of estrogen on breast cancer cells 

Most of the estrogen in women's bodies is made by the ovaries. Estrogen makes hormone-receptor-positive breast cancers grow. So reducing the amount of estrogen or blocking its action can reduce the risk of early-stage hormone-receptor-positive breast cancers coming back (recurring) after surgery. Hormonal therapy medicines can also be used to help shrink or slow the growth of advanced-stage or metastatic hormone-receptor-positive breast cancers.

Hormonal therapy medicines are NOT effective against hormone-receptor-negative breast cancers.

There are several types of hormonal therapy medicines, including aromatase inhibitors, selective estrogen receptor modulators, and estrogen receptor downregulators.

In some cases, the ovaries and fallopian tubes may be surgically removed to treat hormone-receptor-positive breast cancer or as a preventive measure for women at very high risk of breast cancer. The ovaries also may be shut down temporarily using medication.

It's important to know that hormonal therapy IS NOT hormone replacement therapy (HRT). HRT isn't used to treat breast cancer. HRT is taken by some women to treat troublesome menopausal side effects such as hot flashes and mood swings. HRT is used to raise estrogen levels that drop after menopause. HRT contains estrogen and can contain progesterone and other hormones. Hormonal therapy is exactly the opposite -- it blocks or lowers estrogen levels in the body.

In this section you can learn more about hormonal therapy:

The medical experts for Hormonal Therapy are:

  • Jennifer Armstrong, M.D., medical oncologist/hematologist, Thomas Jefferson University Health System, Philadelphia, PA
  • Marisa Weiss, M.D., president and founder of Breastcancer.org; breast radiation oncologist, Thomas Jefferson University Health System, Philadelphia, PA
  • Lisa Weissmann, M.D., medical oncologist/hematologist, Mt. Auburn Hospital, Cambridge, MA

These experts are members of the Breastcancer.org Professional Advisory Board, including more than 60 medical experts in breast cancer–related fields.

The Hormonal Therapy section is made possible by an unrestricted educational grant from Pfizer Oncology.

Hormonal therapy is not HRT

Hormonal (anti-estrogen) therapy works against hormone-receptor-positive breast cancer. It is completely different from hormone replacement therapy (HRT), which some women take during or following menopause. HRT is not a breast cancer treatment, and for women with a breast cancer diagnosis, HRT is considered relatively unsafe.

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