title: A brief review of the 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 meta-analysis 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, 61 Lincoln's Inn Fields, WC2A 3PX, London, UK. j.cuzick@icrf.icnet.uk
authors.forename: J
authors.initials: J
authors.lastname: Cuzick
mesh_terms: D000328:Adult; D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000517:prevention & control; D002986:Clinical Trials as Topic; D016889:Endometrial Neoplasms / Q000139:chemically induced*; D005260:Female; D019584:Hot Flashes / Q000139:chemically induced; D006801:Humans; D008599:Menstruation Disturbances / Q000139:chemically induced; D015201:Meta-Analysis as Topic; D008875:Middle Aged; D020849:Raloxifene Hydrochloride / Q000627:therapeutic use; D012307:Risk Factors; D013629:Tamoxifen / Q000009:adverse effects / Q000627:therapeutic use*
chemical_list: D018931:Antineoplastic Agents, Hormonal; D013629:Tamoxifen; D020849:Raloxifene Hydrochloride