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Initial Results of STAR
In April 2006, researchers announced the initial results of STAR, which showed that
raloxifene may be as effective as tamoxifen at preventing breast cancer in women at
high risk for the disease. Specifically, the results showed that women who were given raloxifene
reduced their risk of breast cancer by 50%. In addition, raloxifene may have fewer potentially
serious side effects than tamoxifen. After an average of four years on raloxifene, women in the
study developed about 36% fewer uterine cancers and 29% fewer blood clots than the women who
took tamoxifen. Click here for more information on these study results.
About Tamoxifen and Raloxifene
Both tamoxifen and raloxifene are "anti-estrogens." Anti-estrogens work by
competing with estrogen to bind to estrogen receptors in breast cancer cells. By blocking
estrogen in the breast, tamoxifen and raloxifene may slow the growth and reproduction of
breast cancer cells.
While tamoxifen and raloxifene may fight estrogen in breast cancer cells, they also
mimic the positive effects of estrogen in other body systems. Post-menopausal women who
take tamoxifen may decrease their risk of heart disease or osteoporosis (a degenerative
bone disease) without having to use hormone replacement therapy
(HRT). Raloxifene is commonly prescribed help prevent and treat osteoporosis. It has been
shown to help build new bone and reduce the risk of fractures.
Raloxifene was approved in December 1997 by the FDA to prevent osteoporosis and has
been in clinical trials for over five years. Tamoxifen has been approved by the FDA to treat
women with breast cancer for more than two decades. Raloxifene (Evista) is currently FDA approved and labeled for
use in preventing/treating osteoporosis in post-menopausal women.
As with all drug treatments, the side effects of tamoxifen and raloxifene vary from
individual to individual. The most common side effect of tamoxifen and raloxifene is a
higher occurrence of hot flashes. Other side effects of tamoxifen include irregular
menstrual cycles, unusual vaginal discharge or bleeding, and irritation of skin around the
vagina. Tamoxifen does not cause menopause in pre-menopausal women, though its side
effects may mimic menopausal symptoms. For most young women who take tamoxifen, the
ovaries continue to act normally and produce estrogen in the same or slightly increased
amounts. In fact, some studies have suggested that tamoxifen may make pre-menopausal women
more fertile.
Side effects of tamoxifen include:
- Hot flashes
- Irregular menstrual cycles
- Unusual vaginal discharge or bleeding
- Irritation of skin around vagina
Tamoxifen also increases a woman's chances of developing serious health problems
including:
- endometrial cancer (cancer of the lining of the uterus)
- deep vein thrombosis (blood clots in large veins, particularly in the legs)
- pulmonary embolism (blood clot in the lung)
- possibly stroke
Because endometrial cancer is a side effect of tamoxifen, women with uterine problems
are not usually candidates for tamoxifen treatment. In addition, pregnant women should not
use tamoxifen because animal studies reveal that the drug may cause serious harm to the
growing fetus. Women with a personal history of severe blood clotting or cataracts should
also avoid tamoxifen.
Women should not take tamoxifen if:
- they are pregnant
- have a history of uterine problems
- have a history of blood clots
- have a history of cataracts
Raloxifene can cause serious side effects including blood clots in the legs and lungs, and
death due to stroke. Women with current or prior blood clots in the legs, lungs, or eyes
should not take Evista. Other potential side effects include:
- hot flashes
- leg cramps
- swelling of the legs and feet
- flu-like symptoms
- joint pain
- sweating
The FDA cautions that raloxifene should not be taken by pre-menopausal women and women who are
or may become pregnant because it may cause harm to the unborn baby. In addition, ralxofene
should not be taken with cholestyramine (a drug used to lower cholesterol levels) or estrogens.
Additional Resources and References
- For information on the National Adjuvant Breast and Bowel Project (NSABP), please visit http://www.imaginis.com/breasthealth/star/nsabp_info.asp
- For NSABP information on STAR and how to enroll, please visit http://www.nsabp.pitt.edu/
- To learn more about tamoxifen, please visit http://www.imaginis.com/breasthealth/tamoxifen.asp
- For NSABP information on STAR, please visit http://www.nsabp.pitt.edu/
- To learn more about raloxifene, please visit http://www.imaginis.com/osteoporosis/osteo_treatment.asp#raloxifene
- The April 30, 2006 Imaginis.com article, "Osteoporosis Drug, Raloxifene, Shows Promise in Preventing Breast Cancer," is available at
http://www.imaginis.com/breasthealth/news/news4.30.06.asp
Updated: November 12, 2007
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