This guide can help you talk with your doctor or nurse about medicine to reduce the risk of breast cancer. It talks about two different medicines. It gives information about benefits, side effects, and cost.
This guide is based on a government-funded review of research reports about using medicine to lower the risk of breast cancer.
This guide does not cover other ways to lower your risk of breast cancer. It does not discuss having surgery to lower the risk of breast cancer. It also does not cover reducing the risk of breast cancer in men because these medicines have not been studied in men.
This guide does not talk about screening for breast cancer. It also does not cover treatments for women who already have breast cancer.
Most women will never get breast cancer. A woman’s risk of breast cancer depends on her age and other risk factors. Most women who get breast cancer have no risk factors other than growing older. And many women who have risk factors other than age never get breast cancer.
The chart below shows how many women (out of 100) will get breast cancer over the next 10 years. The risk of developing breast cancer increases with age. By finding your current age, you will see the risk of someone in your age group.
|Estimated risk for women in the United States. This information comes from Surveillance, Epidemiology and End Results (SEER) Cancer Statistics Review, 1975–2005, National Cancer Institute.|
|30 to 39||Less than 1 in 100|
|40 to 49||About 1 in 100|
|50 to 59||About 2 in 100|
|60 to 69||About 3 in 100|
|70 to 79||About 4 in 100|
Breast cancer is a malignant (muh-LIG-nent) tumor that starts with cells in the breast. Malignant means that the cells are cancerous and may spread to other tissue in the breast. Sometimes the cancer cells spread outside the breast to other parts of the body. This means they metastasize (meh-TASS-ta-size).
Ducts in the breast carry milk to the nipple. Most breast cancers start in the cells that make up the milk ducts. Some breast cancers start in the lobules (glands where breast milk is made).
A non-invasive breast cancer is a growth of abnormal cells found in the breast. The cells have not spread to other tissue in the breast or other parts of the body.
With invasive breast cancer, the abnormal cells have spread beyond the place where they started. Invasive breast cancer can start in the milk ducts or the lobules. But “invasive” means that the cancerous cells have spread to other breast tissue.
Two different medicines can reduce the risk of breast cancer for women who have never had breast cancer before.
To reduce the risk of breast cancer, tamoxifen or raloxifene must be taken once every day for up to 5 years.
Estrogen is a natural hormone found in the body. Some breast cancers use estrogen to grow. There is a place on some breast cancer cells, called a receptor, where estrogen can attach. This type of breast cancer is called estrogen-receptor positive cancer.
Tamoxifen and raloxifene work by blocking estrogen. They attach to the receptor, so estrogen can’t. Without estrogen, this type of breast cancer cell can’t multiply and grow.
Some breast cancers do not have estrogen receptors. This type of breast cancer is called estrogen-receptor negative cancer. It is not as common, but it is harder to treat.
For women who have never had breast cancer, both tamoxifen and raloxifene reduce invasive breast cancer risk by about 50 percent.
For example, this chart shows the overall risk for women in the United States age 50 to 59. Their risk of getting invasive breast cancer in the next 10 years is about 2 in 100. This means that out of every 100 women, about 2 will get breast cancer. If all 100 of these women take medicine to reduce the risk of breast cancer, about half as many (1 woman) will get breast cancer.
Raloxifene does not lower the risk of non-invasive breast cancers (LCIS and DCIS). Research can’t tell us yet about tamoxifen and non-invasive breast cancers.
Both tamoxifen and raloxifene have common side effects. They both can cause hot flashes. Tamoxifen can cause vaginal symptoms, like itching, dryness, or discharge. Raloxifene can cause leg cramps.
Some women who have taken tamoxifen or raloxifene have had a stroke. Research studies have found that the number of strokes in women taking these medicines is about the same as in women not taking these medicines. Talk with your doctor or nurse about your risk for stroke.
Other serious and life-threatening side effects can also happen.
For every 100 women who take tamoxifen or raloxifene for 5 years, the medicine will cause a blood clot or endometrial cancer in about 1 woman.
Taking raloxifene or tamoxifen reduces a woman’s risk of some kinds of breast cancer. Some women who take these medicines will still get breast cancer.
Taking the medicines does not reduce the risk of dying from breast cancer. It also does not mean a woman will live longer. It is not clear why this is the case. Maybe the medicines reduce the kinds of breast cancers that are easiest to treat.
Most women will never get breast cancer. But some women are at higher risk than others. Talk with your doctor or nurse about your risk of breast cancer.
Tamoxifen and raloxifene can lower the risk of getting some kinds of breast cancer. These medicines also can raise the risk of serious problems. Talk with your doctor or nurse about your risk for serious problems from these medicines.
Think about these questions.
|Drug Name||Brand Name||Dose1||Price Per Month2|
|Raloxifene||Evista®||60 mg once a day3||NA||$115|
|Tamoxifen||Nolvadex®||20 mg once day for 5 years||$115||$245|
The information in this guide comes from a detailed review of 123 research reports. The review is called Comparative Effectiveness of Medications To Reduce the Risk of Primary Breast Cancer in Women (2009) and was written by the Oregon Evidence-based Practice Center.
The Agency for Healthcare Research and Quality (AHRQ) created the Eisenberg Center at Oregon Health & Science University to make research helpful for consumers. This guide was written by Erin Davis, B.A., Martha Schechtel, R.N., Bruin Rugge, M.D., and David Hickam, M.D., of the Eisenberg Center. Women at high risk for breast cancer helped the Eisenberg Center develop this guide.
For free print copies of this guide, call 800-358-9295. Ask the Publications Clearinghouse for AHRQ Publication Number: 09(10)-EHC028-A
For more information about breast cancer, visit the MedlinePlus Web site.
For more information about breast cancer prevention, visit the National Cancer Institute Web site.