Right now, it looks as if raloxifene and tamoxifen offer the same protection against breast cancer — about 80% reduction in risk — for post-menopausal women at high risk with no personal history of the disease. But taking raloxifene seems to involve less risk for developing blood clots, cataracts, and uterine cancer.
It's important to remember that these women have only been followed for 4 years after taking raloxifene. Tamoxifen has been studied for more than 30 years. As these women are followed longer, we will have a better idea if raloxifene has side effects that haven't been seen yet.
If you are at increased risk for breast cancer, you will want to work with your doctor to find a plan aimed at lowering your risk that suits you and your lifestyle.
In today's era of personalized medicine, doctors get to know the whole patient in order to make the best customized treatment recommendations possible. Like a detective, your doctor needs to gather facts about your medical conditions, risk factors, social considerations, ability, and willingness to get regular care, personal style of making decisions, and approach to health care. Weighing the risks and benefits of any protective treatment plan takes a lot of time and thought.
For example, consider an obese woman with a high risk of breast cancer who also smokes. The benefit of a SERM like tamoxifen or raloxifene to reduce her risk of breast cancer might be offset by her higher-than-average risk of clot and stroke. But if that woman has a strong family history of breast cancer AND a prior breast biopsy showing atypical ductal hyperplasia, the reduced breast cancer risk is probably worth the increased risk of blood clots. Taking medication also is a reasonable alternative to aggressive risk reduction through prophylactic mastectomy.
Raloxifene also has been studied in women with a history or at high risk of heart disease. The study is called the RUTH Trial (Raloxifene Used for the Heart). Because raloxifene can improve blood cholesterol levels by lowering "bad" cholesterol (low-density lipoprotein, or LDL) and increasing "good" cholesterol (high-density lipoprotein, or HDL), researchers wanted to test whether it could reduce women's heart problems. But after more than 5 years of follow-up, no real improvement was noted. This isn't surprising, because tamoxifen also improves blood cholesterol results — and also, over time, doesn't reduce heart problems.
Studies like the RUTH and STAR Trials help women and their doctors know the tools available to help women be as healthy as possible — including avoiding or lowering the risk of specific illnesses. But any decisions about medicine require a careful whole-person evaluation.
Any risk reduction plan has to include careful methods of early detection. At a minimum, this means yearly mammography, physical exam by your doctor, and regular breast self-examination. For women at especially increased risk (with a breast cancer gene abnormality or a very strong family history of breast cancer), it means a mammogram alternating with MRI scanning every year (so you get a screening every 6 months). You can also reduce your risk by making everyday lifestyle choices, which may be hard to stick to but are really important:
After these basic steps you may want to try to reduce your risk even further. You may consider medications such as those discussed in this study. And you might consider protective surgery.
When you're ready to consider taking another step to reduce your risk of breast cancer, talk to your doctor about raloxifene or tamoxifen. Either medicine is taken once a day for 5 years. But that's not an irreversible decision. While you're taking the medicine, you and your doctor will constantly evaluate your situation. If you have unpleasant side effects that don't improve after a few months, you can change your plan.
Stay tuned to Breastcancer.org for the latest information on medications and other options that can reduce your risk of breast cancer.
Reviewed study: "Raloxifene as Effective as Tamoxifen in Reducing Risk of Invasive Breast Cancer in Post-menopausal Women" by V. Vogel and others, American Society of Clinical Oncology Annual Meeting, June 2006, Abstract LBA5, and Journal of the American Medical Association, June 21, 2006
Is this for me? If you're a post-menopausal woman with a high risk of invasive breast cancer and are considering taking medication to reduce that risk, you might want to read this article.
What question is the study trying to answer? The researchers wanted to see if raloxifene (brand name: Evista) was as effective as tamoxifen in reducing the risk of invasive breast cancer in post-menopausal women who have never had breast cancer. The researchers also wanted to know whether raloxifene caused any side effects.
Raloxifene and tamoxifen are both SERMs (selective estrogen receptor modulators). SERMs block the action of estrogen in breast tissue by sitting in the estrogen receptors on breast cells. Tamoxifen has been the most widely used SERM to reduce the risk of breast cancer in high-risk, post-menopausal women. In studies of raloxifene to treat osteoporosis, researchers noticed that the women taking raloxifene had a lower risk of invasive breast cancer. Those observations led to the study reviewed here.
Study design: More than 19,700 post-menopausal women with an increased risk of breast cancer but with no personal history of the disease were randomly assigned to take either raloxifene or tamoxifen once a day for 5 years.
About 9% of the women had been diagnosed with LCIS (lobular carcinoma in situ), a precancerous condition in which abnormal cells are growing in the milk glands. About 23% of the women had a history of either atypical ductal hyperplasia or atypical lobular hyperplasia, conditions in which abnormal cells are growing in the breast. Both of these conditions are associated with an increased risk of breast cancer.
About half of the women in the study had a mother or sister who had been diagnosed with breast cancer.
The women's ages ranged from 35 to more than 75 years old (the average age was about 58). Most women (94%) were white. The women were followed for about 4 years.
The main goal of the study was to see whether raloxifene or tamoxifen lowered the risk of breast cancer the most. The researchers also noted whether the women developed any of the following conditions:
This study was conducted by the National Surgical Adjuvant Breast and Bowel Project and is known as the STAR (Study of Tamoxifen and Raloxifene) Trial.
Study results: The researchers found that raloxifene was as effective as tamoxifen in reducing the risk of breast cancer in post-menopausal women at increased risk but with no personal history of the disease:
Women who took raloxifene had a lower risk of developing several side effects:
The risk of developing one side effect, non-invasive breast cancer, was about 30% lower in women who took tamoxifen. But this difference wasn't statistically significant.
There were no differences between women taking raloxifene and those taking tamoxifen for risk of heart disease, stroke, or weak or broken bones.
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