Weighing the Risks and Benefits of Tamoxifen Treatment for Preventing Breast Cancer

• Published in: JNCI : Journal of the National Cancer Institute 1999-11, Vol.91 (21), p.1829-1846
• Main Authors: Gail, Mitchell H., Costantino, Joseph P., Bryant, John, Croyle, Robert, Freedman, Laurence, Helzlsouer, Kathy, Vogel, Victor
• Format: Article
• Language: English
• Subjects: Age Factors; Anticarcinogenic Agents - adverse effects; Anticarcinogenic Agents - therapeutic use; Antineoplastic agents; Biological and medical sciences; Breast Neoplasms - pathology; Breast Neoplasms - prevention & control; Carcinoma in Situ; Cataract - prevention & control; Chemotherapy; Controlled Clinical Trials as Topic; Counseling; Education; Endometrial Neoplasms - chemically induced; Estrogen Receptor Modulators - adverse effects; Estrogen Receptor Modulators - therapeutic use; Female; Fractures, Bone - epidemiology; Fractures, Bone - prevention & control; Humans; Medical sciences; National Institutes of Health (U.S.); Neoplasm Invasiveness; Patient Education as Topic; Pharmacology. Drug treatments; Pulmonary Embolism - chemically induced; Risk; Risk Factors; Selective Estrogen Receptor Modulators - adverse effects; Selective Estrogen Receptor Modulators - therapeutic use; Stroke - chemically induced; Tamoxifen; Tamoxifen - adverse effects; Tamoxifen - therapeutic use; United States; Venous Thrombosis - chemically induced
• ISSN: 0027-8874; 1460-2105
• DOI: 10.1093/jnci/91.21.1829

BACKGROUND: In response to findings from the Breast Cancer Prevention Trial that tamoxifen treatment produced a 49% reduction in the risk of invasive breast cancer in a population of women at elevated risk, the National Cancer Institute sponsored a workshop on July 7 and 8, 1998, to develop information to assist in counseling and in weighing the risks and benefits of tamoxifen. Our study was undertaken to develop tools to identify women for whom the benefits outweigh the risks. METHODS: Information was reviewed on the incidence of invasive breast cancer and of in situ lesions, as well as on several other health outcomes, in the absence of tamoxifen treatment. Data on the effects of tamoxifen on these outcomes were also reviewed, and methods were developed to compare the risks and benefits of tamoxifen. RESULTS: The risks and benefits of tamoxifen depend on age and race, as well as on a woman's specific risk factors for breast cancer. In particular, the absolute risks from tamoxifen of endometrial cancer, stroke, pulmonary embolism, and deep vein thrombosis increase with age, and these absolute risks differ between white and black women, as does the protective effect of tamoxifen on fractures. Tables and aids are developed to describe the risks and benefits of tamoxifen and to identify classes of women for whom the benefits outweigh the risks. CONCLUSIONS: Tamoxifen is most beneficial for younger women with an elevated risk of breast cancer. The quantitative analyses presented can assist health care providers and women in weighing the risks and benefits of tamoxifen for reducing breast cancer risk.