Linda S. Kinsinger, MD, MPH; Russell Harris, MD, MPH; Steven H. Woolf, MD, MPH; Harold C. Sox, MD; Kathleen N. Lohr, PhD
Disclaimer: The authors of this article are responsible for its contents, including any clinical or treatment recommendations. No statement in this article should be construed as an official position of the U.S. Agency for Healthcare Research and Quality, the U.S. Department of Defense, or the U.S. Department of Health and Human Services.
Acknowledgments: The authors thank David Atkins, MD, MPH, Director; Dana Best, MD, MPH; and Eve Shapiro of the Agency for Healthcare Research and Quality Clinical Prevention Program. They thank Carmen Lewis, MD, MPH, and Margaret Wooddell, MA, for assistance in reviewing the studies of tamoxifen and raloxifene cited in this paper; Audrina J. Bunton, BA, and Lynn Whitener, MSLS, DrPH, of University of North Carolina, and Sonya Sutton, BSPH, and Loraine Monroe of the Research Triangle Institute; and Bahjat Qaqish, MD, PhD, for statistical assistance.
Grant Support: This study was developed by the Research Triangle Institute-University of North Carolina Evidence-based Practice Center under contract to the Agency for Healthcare Research and Quality (Contract No. 290-97-0011), Rockville, Maryland.
Requests for Reprints: Reprints are available from the AHRQ Web site at www.ahrq.gov (click on Preventive Services) and in print through the AHRQ Publications Clearinghouse (800-358-9295).
Current Author Addresses: Dr. Kinsinger: Program on Prevention, CB# 7508, Wing D, Room 383, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7508.
Dr. Harris: Cecil G. Sheps Center for Health Services Research, CB# 7590, University of North Carolina at Chapel Hill, 725 Airport Road, Chapel Hill, NC 27599-7590.
Dr. Woolf: Department of Family Practice, Virginia Commonwealth University, 3712 Charles Stewart Drive, Fairfax, VA 22033.
Dr. Sox: American College of Physicians-American Society of Internal Medicine, 190 N. Independence Mall West, Philadelphia, PA 19106-1572.
Dr. Lohr: Research Triangle Institute, 3040 Cornwallis Road, Research Triangle Park, NC 27709-2194.
Chemoprevention offers promise as a strategy for reducing morbidity and mortality from breast cancer in women. This review examined the evidence for the effectiveness of chemoprevention in women without a history of breast cancer.
MEDLINE (1966 to December 2001).
English-language, randomized, controlled trials (RCTs) of chemoprevention of breast cancer in women without a previous diagnosis of breast cancer were examined, and 4 relevant trials, 3 involving tamoxifen and 1 involving raloxifene, were selected. Trials that provided data on the harms of tamoxifen or raloxifene, studies of the costs of chemoprevention, and studies of risk assessment were also reviewed.
Four reviewers independently abstracted data on key variables, including study population, sample size, randomization, treatment, and outcomes.
The largest of the RCTs of tamoxifen reported a 49% reduction in relative risk (0.51 [95% CI, 0.39 to 0.66]) for invasive cancer among women with an estimated 5-year breast cancer risk of at least 1.66%. The other tamoxifen trials did not observe a statistically significant benefit, but only a few women in each trial took tamoxifen during the entire study period. The raloxifene study of postmenopausal women with osteoporosis found a 76% reduction in relative risk (0.24 [CI, 0.13 to 0.44]) for invasive breast cancer. Tamoxifen and raloxifene were effective only against estrogen receptor-positive tumors. Both drugs increased risk for venous thromboembolic disease and hot flashes; tamoxifen increased risk for endometrial cancer and stroke.
Tamoxifen and raloxifene reduce the incidence of estrogen receptor-positive breast cancer in women. The relative risk reduction seems similar across all breast cancer risk groups. The absolute risk reduction varies by risk factors for breast cancer, however, and must be balanced against the potential harms to judge the appropriateness of treatment for individual women.
Table 1. Summary of Four Randomized, Controlled Trials of Breast Cancer Chemoprevention
Table 2. Comparison of Randomized, Controlled Trials of Breast Cancer Chemoprevention
Table 3. Adverse Events in Four Randomized, Controlled Trials of Breast Cancer Chemoprevention
Benefits and harms of chemoprevention with tamoxifen per 10 000 women in three age groups.
Appendix Table 1. Breast Cancer Chemoprevention: Inclusion and Exclusion Criteria
Appendix Table 2. Search Strategy Results for Breast Cancer Chemoprevention
Appendix Table 3. Review Criteria for Abstracts and Articles in Breast Cancer Chemoprevention
Appendix Table 4. Summary Results from Literature Searches and Reviews
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Kinsinger LS, Harris R, Woolf SH, Sox HC, Lohr KN. Chemoprevention of Breast Cancer: A Summary of the Evidence for the U.S. Preventive Services Task Force. Ann Intern Med. ;137:59–69. doi: 10.7326/0003-4819-137-1-200207020-00017
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Published: Ann Intern Med. 2002;137(1):59-69.
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