Coping and support (1)
- Support groups: Find information, encouragement and camaraderie
Prevention (5)
- Breast cancer chemoprevention: Medicines that reduce breast cancer risk
- Genetic testing for breast cancer: Psychological and social impact
- Prophylactic mastectomy: Breast cancer prevention for high-risk women
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- Atypical hyperplasia of the breast
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- Types of breast cancer
- Biopsy: Types of biopsy procedures used to diagnose cancer
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- Breast augmentation
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Breast cancer chemoprevention: Medicines that reduce breast cancer risk
Preventive medications (chemoprevention) reduce breast cancer risk for women at high risk of developing the disease. Find out how these medications work plus associated side effects and health risks.
By Mayo Clinic staffIf you're at high risk of breast cancer, you may be able to improve your odds of staying cancer-free by taking certain medicines, an approach known as chemoprevention or chemoprophylaxis.
The best-known options are selective estrogen receptor modulators (SERMs) — tamoxifen and raloxifene (Evista). Both drugs have Food and Drug Administration (FDA) approval for the prevention of breast cancer in high-risk women.
Research continues to explore the breast cancer prevention potential of tamoxifen, raloxifene and several new medications, and recommendations for their use undoubtedly will change.
Tamoxifen
How it works
Tamoxifen blocks the effects of estrogen, a reproductive hormone that influences the growth and development of many breast tumors. Tamoxifen is usually prescribed as a pill you take once a day by mouth. For breast cancer prevention, tamoxifen is typically taken for a total of five years.
Who it's for
Tamoxifen is FDA approved for breast cancer prevention in high-risk women age 35 and older, whether or not they've gone through menopause. Generally speaking, you might consider chemoprevention with tamoxifen if:
- Your Gail model risk score is greater than 1.66 percent. The Gail model is a tool doctors use to predict future risk of developing breast cancer based on factors such as your age, reproductive history and family history.
- You're at high risk of developing breast cancer — for instance, you've been diagnosed with a precancerous condition such as atypical hyperplasia or lobular carcinoma in situ (LCIS).
- You have a strong family history of breast cancer.
- You don't have a history of blood clots.
- You've had a hysterectomy.
Common side effects
Common side effects of tamoxifen include:
- Hot flashes
- Vaginal discharge
- Vaginal dryness
- Menstrual irregularities
- Bladder or urinary problems
- Nausea
Risks
Rarely, taking tamoxifen may cause:
- Blood clots
- Endometrial cancer or uterine cancer
- Cataracts
- Stroke
Taking tamoxifen doesn't guarantee that you'll remain cancer-free. Unless you're at high risk of developing breast cancer, the potential risks of tamoxifen may outweigh the benefits for you.
Raloxifene
How it works
Raloxifene is also prescribed in pill form, to be taken by mouth once a day. Like tamoxifen, raloxifene works by blocking estrogen's effects in the breast and other tissues. Unlike tamoxifen, raloxifene doesn't exert estrogen-like effects on the uterus.
Who it's for
Raloxifene is currently approved by the FDA for reducing breast cancer risk in high-risk women who are past menopause (postmenopausal). You're considered at high risk if you score greater than 1.66 percent on the Gail model. Raloxifene is also approved for prevention and treatment of the bone-thinning disease osteoporosis in postmenopausal women.
Common side effects
Common side effects of raloxifene include:
- Hot flashes
- Vaginal discharge
- Vaginal dryness or irritation
- Bladder or urinary problems
- Joint and muscle pain
- Weight gain
Risks
Health risks associated with raloxifene are similar to those associated with tamoxifen. Both drugs carry an increased risk of blood clots. However, raloxifene may be associated with fewer cases of endometrial and uterine cancers than is tamoxifen. Raloxifene may also be linked to fewer strokes than tamoxifen in women at average risk of heart disease. But if you have heart disease or you have multiple risk factors for heart disease, such as high cholesterol, high blood pressure and obesity, raloxifene may actually increase your risk of strokes.
(1 of 2)
- Medicines to reduce breast cancer risk. American Cancer Society. http://www.cancer.org/docroot/CRI/content/CRI_2_6X_Tamoxifen_and_Raloxifene_Questions_and_Answers_5.asp?sitearea. Accessed Dec. 5, 2008.
- FDA approves new uses for Evista (raloxifene hydrochloride). Food and Drug Administration Center for Drug Evaluation and Research. http://www.fda.gov/cder/Offices/OODP/whatsnew/raloxifene.htm. Accessed Dec. 8, 2008.
- Pruthi S, et al. A multidisciplinary approach to the management of breast cancer, part 1: Prevention and diagnosis. Mayo Clinic Proceedings. 2007;82:999.
- Land SR, et al. Patient-reported symptoms and quality of life during treatment with tamoxifen or raloxifene for breast cancer prevention: The NSABP study of tamoxifen and raloxifene (STAR) P-2 trial. Journal of the American Medical Association. 2006;295:2742.
- The study of tamoxifen and raloxifene (STAR): Questions and answers. National Cancer Institute. http://www.cancer.gov/Templates/doc.aspx?viewid=0123E12E-CCD6-47BC-9964-D5DD6CB0399E. Accessed Dec. 5, 2008.
- Harris RE, et al. Breast cancer and nonsteroidal anti-inflammatory drugs: Prospective results from the Women's Health Initiative. Cancer Research. 2003;63:6096.
- Terry MB, et al. Association of frequency and duration of aspirin use and hormone receptor status with breast cancer risk. Journal of the American Medical Association. 2004;291:2433.
- Agrawal A, et al. NSAIDs and breast cancer: A possible prevention and treatment strategy. International Journal of Clinical Practice. 2008;62:444.
- Chan K, et al. Chemoprevention of breast cancer for women at high risk. Seminars in Oncology. 2006;33:642.
- Mosca L, et al. Effect of raloxifene on stroke and venous thromboembolism according to subgroups in postmenopausal women at increased risk of coronary heart disease. Stroke. In press. Accessed Dec. 12, 2008.
