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Raloxifene is a Selective Estrogen Receptor Modulator (SERM) that blocks the effects of estrogen similar to tamoxifen. It was originally used for the prevention and treatment of osteoporosis in women. However, several early clinical studies suggested a role in decreasing invasive breast cancer in postmenopausal women.
A large clinical trial, the Study of Tamoxifen and Raloxifene (STAR), was performed to determine the extent of invasive breast cancer risk reduction in high-risk post-menopausal women between tamoxifen and raloxifene. In the most recent 2010 STAR update with an 81-month post treatment follow-up, researchers identified a 50% risk reduction in patients taking tamoxifen and 38% risk reduction in those taking raloxifene. There was no statistical significant difference between raloxifene and tamoxifen in breast cancer risk reduction.
The major advantage of raloxifene over tamoxifen treatment is the presence of fewer serious side effects. The benefits of raloxifene include significantly lower risks for uterine cancers, thromboembolic events, blood clots and cataracts as compared to tamoxifen. One study showed that raloxifene lowered the risk for uterine cancer by half compared to women who did not take the medication, while tamoxifen increased the risk for uterine cancer.
The STAR trial included only post-menopausal women who are high-risk based on the risk assessment using the Gail Model, but did not look specifically at women with BRCA mutations, so the benefits of raloxifene in BRCA mutation carriers remain uncertain.
Raloxifene is an effective preventative strategy for the reduction of invasive breast cancer in healthy women. Women who consider taking raloxifene should discuss the benefits, risks and limitations with their health care team, including experts in managing high-risk women.