Research summary
April 2006
Research shows raloxifene (Evista®) as effective as tamoxifen in reducing the risk of breast cancer, but with fewer side effects
Summary
Initial results of a trial involving 19,000 post-menopausal women at increased risk of developing breast cancer have found the drug raloxifene (Evista®), currently used to treat osteoporosis, is as effective as tamoxifen in reducing the risk of breast cancer but with fewer side effects. These initial results from the STAR trial (Study of tamoxifen and raloxifene) were released by the National Cancer Institute in the United States on 18 April.
Both tamoxifen and raloxifene were found to reduce the risk of breast cancer in post-menopausal women by about 50 per cent. However, the women who took raloxifene had 36 per cent fewer cancers of the uterus and 29 per cent fewer blood clots compared to the women who took tamoxifen as part of the trial.
Both drugs were associated with a similar increase in risk of stroke and heart attack. However, while tamoxifen was associated with a decreased risk of pre-invasive forms of breast cancer known as ductal carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS) raloxifene was not.
At this time there is no evidence that either drug decreases the risk of death from breast cancer.
National Breast Cancer Centre comment
The STAR trial is focused on the prevention of breast cancer in healthy women who have never had the disease but are at increased risk of developing breast cancer. It is not looking at raloxifene as a form of treatment for women with breast cancer.
These trial results are promising for post-menopausal women at increased risk of developing breast cancer.
The median follow-up of women on this trial was four years. Longer follow-up of these women will address some unanswered questions such as the significance of no change in the incidence of pre-invasive forms of breast cancer.
Trials have previously looked at the role tamoxifen could play in the prevention of breast cancer in women who have never had the disease, but it was determined the serious side effects of tamoxifen outweighed the benefits of lowering the risk of breast cancer for Australian women.
The trial results for raloxifene showing a reduction in some of the serious side effects associated with tamoxifen is good news. However, there was no difference in the risk of stroke or heart attack.
It is important to note that while these results are promising, they are only relevant to the population of post-menopausal women who are at increased risk of developing breast cancer.
Raloxifene is currently only available on the Pharmaceutical Benefits Scheme (PBS) for the treatment of osteoporosis.
Click here for more information about factors that may increase a woman’s risk of developing breast cancer.