Hormone Therapy for Breast Cancer Treatment

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Most cases of breast cancer are fueled by the hormones estrogen and progesterone. Hormone therapy, also called endocrine therapy, is used to remove or block hormones and stop or slow down the growth of cancer cells. If your cancer is hormone-sensitive, then hormone therapy may be part of your treatment plan.

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 estrogen-responsive cancer cells, thus reducing your risk of recurrence. For breast cancer that is estrogen receptor-negative, hormonal therapy is not effective.

Anti-Estrogen Hormone Drugs

Hormones can be lowered by drugs and/or by surgery. Two classes of drugs are used for hormone therapy: selective estrogen receptor modulators (SERMs) and aromatase inhibitors (AIs). These are given based on your menopausal status and your breast cancer diagnosis.

Below are commonly-used prescription drugs, plus information on how long they need to be taken.

Early-Stage Breast Cancer

Menopausal
Status
Anti-Estrogen Drug Dosage Duration
Pre- Tamoxifen 2 to 5 years
Pre- Combination of ovarian-suppression drugs (SERMs and AIs) 5 years (clinical trials)
Post- Aromatase inhibitor 5 years (Continuing for an additional 5 may improve disease-free survival.)

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. Tamoxifen may be given for two years and followed by Aromasin for three years in some cases.

For women treated with tamoxifen for five years, either continuing the tamoxifen or switching to an AI for an additional five years is effective in reducing the risks of recurrence; there is data suggesting an improvement in overall survival, too.


Metastatic Disease

Menopausal
Status
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- Toremifene Until no longer effective
Post- Faslodex injection For disease no longer responding to tamoxifen or Fareston (toremifene)
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

Note that, in general, patients with high-risk feature tumors (e.g., node-positive disease or T3 or higher tumors) should take hormonal therapy for 10 years in order to decrease the risk of recurrence.

Drug Side Effects

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 natural 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

Alternatives for Hormone Suppression

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. It is critical to discuss this issue with your doctor before starting treatment.

A Word From Verywell

Knowing the hormone receptor status of your breast cancer is a critical factor when determining the appropriate treatment. In some cases, your receptor status can change, though this is more common when cancer recurs. Fortunately, there are effective hormonal treatments for both early-stage cancer as well as metastatic disease.

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