title: A brief review of the International Breast Cancer Intervention Study (IBIS), the other current breast cancer prevention trials, and proposals for future trials.
abstract: The available results from breast cancer chemoprevention trials are reviewed. Four trials using tamoxifen have been performed, of which three have reported efficacy results. A fifth trial using raloxifene has also been published. The largest tamoxifen trial shows approximately a 50% reduction in breast cancer incidence in the short term, but the two smaller trials have not found any incidence reduction. Greater agreement exists for side effects: thromboembolic disease and endometrial cancers are raised about 2- to 3-fold when tamoxifen is used for 5 years. The possible reasons for the discrepancy in breast cancer reduction are explored. A review of trial parameters does not clearly explain this difference, and a metanalysis indicates that all results are compatible with a 42% reduction in short-term incidence. Several important questions remain about the clinical implication of this result, including the effect on mortality, the appropriate risk groups for chemoprevention, and the long-term effects on incidence. Continued follow-up of these trials is crucial for resolving these issues.
authors.affiliation: Department of Mathematics, Statistics, and Epidemiology, Imperial Cancer Research Fund, London, United Kingdom. j.cuzick@icrf.icnet.uk
authors.forename: J
authors.initials: J
authors.lastname: Cuzick
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D001943:Breast Neoplasms / Q000517:prevention & control*; D002986:Clinical Trials as Topic; D005260:Female; D006801:Humans; D008875:Middle Aged; D020849:Raloxifene Hydrochloride / Q000627:therapeutic use*; D020845:Selective Estrogen Receptor Modulators / Q000627:therapeutic use*; D013629:Tamoxifen / Q000627:therapeutic use*
chemical_list: D020845:Selective Estrogen Receptor Modulators; D013629:Tamoxifen; D020849:Raloxifene Hydrochloride