04/11/2003 - News

More than two million women in US could benefit from tamoxifen

By: Susan Aldridge, medical journalist, PhD


While millions of women in the US are eligible for tamoxifen to prevent breast cancer, only a percentage can expect an overall benefit.

It's already known that women with an increased risk of breast cancer will enjoy a 49 per cent reduction in this risk if they take the preventive drug tamoxifen for five years. Based on this, the Food and Drug Administration in the US approved tamoxifen for chemopreventive treatment for women over 35 who have a five year breast cancer risk of 1.67 per cent, or more.

But tamoxifen is also linked with an increased risk of adverse effects like thrombosis and endometrial cancer. Researchers at the National Cancer Institute have tried to clarify the situation by assessing the benefit to risk equation for different groups of women on tamoxifen. Of the women in the 35 to 79 age group in the US, 15.5 per cent are eligible for tamoxifen based upon their breast cancer risk. Within this, the percentages vary with age and risk - 18.7 per cent of white women are eligible, compared to 5.7 per cent of black women and 2.9 per cent of Hispanic women.

When risks of tamoxifen are included, 4.9 per cent of white women - about two million - can expect overall benefit from the drug. For black women, the percentage is only 0.6 per cent, because this group is more susceptible to the drug's adverse effects.

Suppose the two million white women who could benefit from tamoxifen actually took it. Then, the researchers say, 28,492 cases of breast cancer would be prevented or deferred. The take-home message from this study is that the decision whether or not to take tamoxifen must be taken only after careful weighing of the risks and benefits for the individual woman.


Journal of the National Cancer Institute 2md April 2003

Created on: 04/11/2003
Reviewed on: 04/11/2003

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