Chemoprevention of breast cancer with tamoxifen and raloxifene

Chemoprevention with tamoxifen or raloxifene is a promising strategy to decrease the incidence of breast cancer. The MORE-trial reported a 76% decrease in the incidence of breast cancer in women who took raloxifene. The results for tamoxifen are contradictory. The BCPT-trial found a 69% and the latest IBIS-trial a 32% decrease in breast cancer incidence, but the Royal Marsden and the first Italian trials showed no benefit for tamoxifen. The recent Italian update found a reduction in the incidence of estrogen-positive breast cancer among a subgroup of women. All investigators found adverse effects of tamoxifen, such as an increased rate of thromboembolic events, endometrial cancer, cataract and hot flushes. Tamoxifen is effective for the chemoprevention of breast cancer. Whether mortality due to breast cancer can be reduced has yet to be examined. Since the selective estrogen receptor modulators are used in healthy women for preventive strategies, their adverse effects should be small. New drugs are to be developed for this purpose.