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 in the body
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 help shrink hormone-receptor-positive breast cancers and reduce the risk of hormone-receptor-positive breast cancers coming back (recurring).
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.
Hormonal therapy medicines are whole-body (systemic) treatment for hormone-receptor-positive breast cancers.
Hormone-receptor-positive breast cancer is the most common type of breast cancer:
- about 80% of breast cancers are estrogen-receptor positive
- about 65% of estrogen-receptor-positive breast cancers are also progesterone-receptor-positive
- about 13% of breast cancers are estrogen-receptor-positive and progesterone-receptor-negative
If a cancer has receptors for either estrogen or progesterone, it's considered hormone-receptor-positive.
There are three different types of hormonal therapy medicines:
- aromatase inhibitors:
- Arimidex (chemical name: anastrozole)
- Aromasin (chemical name: exemestane)
- Femara (chemical name: letrozole)
- SERMs (Selective Estrogen Receptor Modulators):
- tamoxifen
- Evista (chemical name: raloxifene)
- Fareston (chemical name: toremifene)
- ERDs (Estrogen Receptor Downregulators):
- Faslodex (chemical name: fulvestrant)
Hormonal therapy medicines also can be used to:
- lower the risk of hormone-receptor-positive breast cancer coming back
- lower the risk of hormone-receptor-positive breast cancer in women who are at high risk but haven't been diagnosed with breast cancer
