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By Mayo Clinic staffHormone therapy is usually prescribed as a pill taken orally once a day beginning after surgery and chemotherapy is completed. Hormonal therapy can be taken at the same time as radiation therapy.
In certain situations your doctor may recommend hormone therapy before an operation in an attempt to shrink the tumor and make the operation easier. The specific type, timing and length of hormone therapy that's right for you depend on your individual medical situation. Below are the most common types of hormone therapy medications used to treat breast cancer.
Tamoxifen
Tamoxifen is a drug that blocks the effects of estrogen in the body. It's in a class of medications known as anti-estrogens or selective estrogen receptor modulators (SERMs). Tamoxifen is typically taken for a total of five years, although research is ongoing to determine the ideal length of treatment with tamoxifen. Tamoxifen can be used by women before or after menopause, as well as by men who have breast cancer.
Common side effects of tamoxifen are similar to the symptoms of menopause and may include:
- Hot flashes
- Vaginal discharge
- Irregular menstrual periods
- Headaches
- Vaginal dryness
Aromatase inhibitors
Aromatase inhibitors are a class of medicines that reduce the amount of estrogen in your body, depriving breast cancer cells of the hormones they need to grow and thrive.
Three aromatase inhibitors are currently used in the treatment of some women with breast cancer:
- Anastrozole (Arimidex)
- Exemestane (Aromasin)
- Letrozole (Femara)
Aromatase inhibitors may be prescribed for postmenopausal women to treat early-stage breast cancer and prevent breast cancer recurrence. They also may be used to slow disease progression in postmenopausal women who have breast cancer that has recurred or spread (metastatic breast cancer). Aromatase inhibitors aren't used to treat breast cancer in women who still have menstrual cycles (premenopausal women) because these medications don't block the production of estrogen from the ovaries.
Treatment options with aromatase inhibitors usually involve one of the following:
- Treatment with tamoxifen for two to five years, followed by treatment with aromatase inhibitors for up to another five years.
- Treatment with aromatase inhibitors alone for five years.
The ideal length of hormone therapy with aromatase inhibitors is still under investigation.
Common side effects of aromatase inhibitors include:
- Hot flashes
- Joint pain and stiffness
- Vaginal bleeding
- Bone thinning
Although tamoxifen and aromatase inhibitors are the most common forms of hormone therapy for breast cancer, other hormonal therapies are available, as well. Talk to your doctor about the specific hormone therapy regimen that's best for you.
- Tamoxifen: Questions and answers. National Cancer Institute. http://www.cancer.gov/cancertopics/factsheet/Therapy/tamoxifen. Accessed June 4, 2010.
- Sabel MS. Oncology. In: Doherty GM. Current Diagnosis & Treatment: Surgery. 13th ed. New York, N.Y.: McGraw-Hill; 2010. http://www.accessmedicine.com/content.aspx?aID=5316764. Accessed June 4, 2010.
- Meric-Bernstam F, et al. Oncology. In: Brunicardi FC, et al. Schwartz's Principles of Surgery. 9th ed. New York, N.Y.: McGraw-Hill; 2010. http://www.accessmedicine.com/content.aspx?aID=5021163. Accessed June 4, 2010.
- Pritchard KI. Adjuvant endocrine therapy for premenopausal women with early stage breast cancer. http://www.uptodate.com/home/index.html. Accessed June 7, 2010.
- Pritchard KI. Adjuvant endocrine therapy for postmenopausal women with early stage breast cancer. http://www.uptodate.com/home/index.html. Accessed June 7, 2010.
- Ellis M, et al. Endocrine therapy of metastatic breast cancer. http://www.uptodate.com/home/index.html. Accessed June 7, 2010.
- Treatment of invasive breast cancer by stage. American Cancer Society. http://www.cancer.org/docroot/CRI/content/CRI_2_4_4X_Treatment_by_Stage_Breast_Cancer_5.asp?sitearea=. Accessed June 4, 2010.
- Giuliano AE. Breast Disorders. In: Doherty GM. Current Diagnosis & Treatment: Surgery. 13th ed. New York, N.Y.: McGraw-Hill; 2010. http://www.accessmedicine.com/content.aspx?aID=5213900. Accessed June 4, 2010.
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