There are strong data to support the hypothesis that tamoxifen reduces the risk of invasive breast cancer in women who are at increased risk for the disease. Results from the Breast Cancer Prevention Trial (BCPT) showed a 49% reduction in the incidence of invasive breast cancer in high-risk women receiving tamoxifen, compared with similar women who took placebo.*Dr Leslie Ford from the National Cancer Institute (NCI), US, says that the question has now changed from ‘does tamoxifen prevent breast cancer?’ to ‘in which groups of women is tamoxifen more beneficial, and how can we weigh the risks and benefits?’ An approach to balancing the risks and benefits of tamoxifen for individual women was discussed at the 90th Annual Meeting of the American Association for Cancer Research [Philadelphia, US; April 1999].