There was no difference in the number of heart attacks between the two groups. The new STAR clinical trial is examining whether raloxifene, a drug similar to tamoxifen, is also effective in preventing invasive breast cancer in women who have not had the disease and whether it offers any benefits over those obtained with tamoxifen. The women who choose to enroll will be randomly assigned to a regimen of 20 mg of tamoxifen or 60 mg of raloxifene daily for five years. They will receive close follow-up examinations, including mammography , physical exam, and gynecologic exam on a regular basis for at least seven years. Women who participate in STAR will not be charged for the cost of either tamoxifen or raloxifene.
Anti-estrogens compete with estrogen to bind to estrogen receptors.
To grow and reproduce, breast cancer cells require the female hormone estrogen. By blocking estrogen in the breast, tamoxifen and raloxifene slow the growth and reproduction of breast cancer cells. While tamoxifen and raloxifene fight estrogen in breast cancer cells, they also mimic the positive effects of estrogen in other body systems. 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.