Between 2% and 15% of women who have been diagnosed with breast cancer will develop contralateral breast cancer--cancer in the opposite breast--depending on age and other factors. Tamoxifen has been shown to reduce the risk of contralateral breast cancer by 47% in women with early-stage primary breast cancer. However, the trials that demonstrated tamoxifen's benefits were done largely in populations of white women, and little data exists on the drug's effects on African American women. In addition, tamoxifen use is associated with an increased risk of thromboembolic events, such as stroke, and the African American population has more risk factors--such as cardiovascular disease and diabetes--for these events compared with the white population.
To determine if there is a difference in the occurrence of contralateral breast cancers and thromboembolic events between African American and white women with breast cancer who are treated with tamoxifen, Worta McCaskill-Stevens, M.D., of the National Cancer Institute, and colleagues pooled data from 13 National Surgical Adjuvant Breast and Bowel Project clinical trials that had included more than 20,000 women.
In women from both ethnic groups who had estrogen-receptor (ER)-positive tumors, tamoxifen use was associated with a similar reduction in contralateral breast cancer. Tamoxifen use was also associated with a similar risk of thromboembolic events in both groups, and the risk of thromboembolic events was greater in women treated with both chemotherapy and tamoxifen compared with women treated with tamoxifen alone. Obesity and age were also risk factors for thromboembolic events. The authors conclude that tamoxifen is equally effective in both African American and white women.
"It is not unreasonable to extrapolate these findings to the prevention setting," the authors write. "Our data therefore provide further support for the need to assess an individual woman's health and personal history, not only her race and ethnicity, to determine the benefits and risks of tamoxifen as a chemopreventive agent."
Contact: National Cancer Institute Press Office, 301-496-6641, NCIPressOfficers@mail.nih.gov
Citation: McCaskill-Stevens W, Wilson J, Bryant J, Mamounas E, Garvey L, James J, et al. Contralateral Breast Cancer and Thromboembolic Events in African American Women Treated With Tamoxifen. J Natl Cancer Inst 2004;96:1762-69.
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