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Hormone Therapy for Breast Cancer

Drugs and Surgery Reduce Risk of Recurrence in Estrogen-Sensitive Breast Cancer


Updated March 31, 2009

Hormone Therapy for Breast Cancer
Most cases of breast cancer are fueled by the hormones estrogen and progesterone. If your cancer is hormone-sensitive, then hormone therapy may be part of your treatment plan. Hormone therapy, also called endocrine therapy, is used to remove or block hormones, to stop or slow down the growth of cancer cells. If your doctor prescribes this for your early stage breast cancer, plan on taking hormonal therapy for five years after completing your primary treatments. The main benefit of this type of therapy is to prevent estrogen from fueling of estrogen responsive cancer cells, thereby reducing your risk of recurrence. For breast cancer that is estrogen-receptor negative, hormonal therapy is not effective.

Drugs and Surgery Can Be Hormonal Therapies
Hormones can be lowered by drugs and by surgery. In pre-menopausal women, the ovaries create most of the estrogen, and after primary treatment, taking Tamoxifen will be sufficient to block estrogen from cancer cells. If needed, for young women with estrogen-sensitive breast cancer, ovaries can be temporarily shut down with ovarian suppression injections. For high-risk women, ovaries can be surgically removed (oophorectomy). Oophorectomy is a significant step to take, as you will no longer be fertile, so discuss this issue with your doctor before starting treatment.

Two Classes of Anti-Estrogen Hormone Drugs
Two classes of drugs are used for hormone therapy, and these are given based on your menopausal status and your breast cancer diagnosis.

Common Side Effects of Hormone Therapy
Having your ovaries shut down or removed, or taking hormone therapy can bring on medical menopause. You may not get all of the symptoms of menopause, but here are some common side effects you may experience from this type of therapy:
  • Hot flashes
  • Night sweats
  • Mood swings
  • Vaginal dryness
  • Fatigue
In Summary
Hormonal therapies are used after surgery and other primary treatments for breast cancer. These help prevent recurrence or disease progression in estrogen-receptor positive breast cancers, preventing estrogen from fueling the growth of estrogen responsive cancer cells. If your doctor prescribes anti-estrogen drugs for you, it is important to take them regularly and for as long as you need them.


National Cancer Institute. Breast Cancer Treatment. Treatment Option Overview: Hormone therapy. Last Modified: 08/01/2008.

American Cancer Society. Detailed Guide: Breast Cancer. Hormone Therapy. Last Revised: 03/02/2009.

National Cancer Institute. Tamoxifen: Questions and Answers. Reviewed: 03/17/2008.

How Hormonal Therapies Are Prescribed for Estrogen Sensitive Breast Cancer

Early-stage breast cancer:
Anti-Estrogen Drug Dosage Duration
Pre- Tamoxifen 2* - 5 years
Pre- Combination of ovarian suppression drugs, SERMs and AIs 5 years (clinical trials)
Post- Aromatase Inhibitor 5 years
* Tamoxifen may be given for two years and followed by Aromasin for three years, in some cases

Metastatic disease:
Anti-Estrogen Drug Dosage Duration
Any Tamoxifen Until no longer effective
Any Intermediate and high-dose estrogens Until no longer effective
Any Aromatase Inhibitors Until no longer effective
Post- Faslodex Injection For disease no longer responding to Tamoxifen or Fareston
Any Megace For disease no longer responding to other hormonal therapies
Any Androgens (male hormones) Used after all other hormonal therapies have become ineffective
Pre- Combination of ovarian suppression drugs, SERMs and AIs Until no longer effective
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