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25 July 2006
Preventative Effect Of Tamoxifen “Non-Existent” For Most Women 
Women taking tamoxifen to prevent breast cancer may be wasting their time, according to a new study from the University of California which found that the drug has little impact on overall mortality rates for most "high risk" women. The study, in the journal CANCER, did however reveal that life expectancy improved when women were at the higher end of breast cancer risk (greater than 3 percent). But the high price of tamoxifen in the U.S. resulted in an extraordinarily high cost-per-life-year-saved, further reducing tamoxifen's utility as a cancer prevention drug for American women, say the researchers. Tamoxifen was developed to treat estrogen-receptor (ER) positive breast cancers but it has also been shown to prevent breast cancer in high risk women. Past studies have found that among women who meet the minimum FDA eligibility criteria for "high risk" (a 5-year risk of breast cancer of at least 1.67 percent), tamoxifen use resulted in a 49 percent reduction in ER positive breast cancers. However, its effect on survival has not been studied until now.
The researchers found that there was no mortality benefit "for women at the lower end of the high risk range for breast cancer." However, life expectancy benefit was seen for women whose 5-year risk reached more than 2 percent. For women at the threshold 5-year risk of 1.67 percent, the researchers calculated a cost of $1,335,690 per-year-of-life-saved, an extraordinarily high cost-to-effectiveness ratio. In contrast, for Canadian women, the researchers calculated $123,780 per-year-of-life-saved. The researchers conclude that it would take a breast cancer risk greater than 3 percent to see benefits from tamoxifen. "The projected benefits of tamoxifen for women at or near the threshold risk for breast cancer (1.67 percent) are very small or non-existent," conclude the authors of the study, and would help only a "relatively small proportion of women." Source: University of California - Davis
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