University of Pennsylvania Cancer Center
Last Modified: May 18, 1998
Tamoxifen has been used for the past twenty years to treat breast cancer and prevent its recurrence. Knowledge of its benefit in preventing breast cancer remained unknown, however. Today researchers from the National Surgical Breast and Bowel Project (NSABP) presented the results of a trial examining the breast cancer prevention benefits of tamoxifen.
13,388 women participated in the placebo controlled, double-blinded randomized clinical trial. Through almost four years of follow-up, the study demonstrated that the drug reduces the incidence of breast cancer by 45% among women at high risk of the disease. "High risk" was determined by looking at each woman's family history of breast cancer, age, pregnancy history, and age at time of menstruation, among other factors.
Of those participating in the trial, 85 women on tamoxifen developed breast cancer, compared to 154 cases in the women assigned to placebo. The study did find an elevated risk of developing endometrial cancer (33 cases on tamoxifen, compared to 14 in placebo); pulmonary embolism (17 versus 6) ; and thrombosis (30 versus 19). Women under 50, however, experience no excess risk of side effects.
Jan 26, 2015 - Tamoxifen and raloxifene can reduce the risk of breast cancer in high-risk women, according to updated guidelines published online May 26 in the Journal of Clinical Oncology. In a related study in the same issue, weekly treatment of metastatic breast cancer with an albumin-bound form of paclitaxel improves survival compared with docetaxel.
Jan 26, 2015