US Pharm. 2015;40(1):10.

London, England—The preventive effect of the breast cancer drug tamoxifen remains virtually constant for at least 20 years, the International Breast Cancer Intervention Study has found. Long-term treatment with tamoxifen to prevent breast cancer was investigated in 7,154 high-risk pre- and postmenopausal women aged 35 to 70 years who received either tamoxifen or placebo daily for 5 years and then were monitored for a mean of 16 years (maximum 22 years). There was a 29% reduction in breast cancer development in tamoxifen subjects versus placebo subjects. The estimated risk of developing breast cancer was 8% in the tamoxifen group versus 12% in the placebo group, equating to 22 women being treated with tamoxifen for each case of breast cancer prevented after 20 years.

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