The drug works against the effects of estrogen on these cells. For the last 20 years, it has been effective for women who have already been treated for breast cancer by helping prevent the original breast cancer from returning or new cancers from developing. There is research demonstrating that it also helps reduce the incidence of breast cancer. However, some side effects have been linked with use of both drugs. There is a small increase in the number of blood clots in the lungs and major arteries of women taking tamoxifen.
Studies show there is also an increased risk of developing uterine cancer or endometrial cancer.
The long-term side effects of both Raloxifene and Tamoxifen are being evaluated in this trial. The group at high risk for developing breast cancer includes all post-menopausal women, women who have a mother, sisters or daughters who had breast cancer, and women who had a breast biopsy that revealed specific abnormalities. Other women may fall into the category based on their lifetime exposure to estrogen. Women who are in the high-risk category should ask their primary care physicians about tamoxifen, raloxifen and the STAR Trial.