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Breast Cancer Treatment: Weighing the Hormonal Options

Tamoxifen has been the standard in hormonal breast cancer treatment for decades. But newer treatments are challenging tamoxifen's superiority.

Arimidex Beats Out Tamoxifen

In the Arimidex trial, women who switched to the aromatase inhibitor fared better than if they stayed on standard tamoxifen.

The study followed 448 postmenopausal women who had been taking tamoxifen for at least two years following breast cancer surgery. The women were randomly assigned to continue taking tamoxifen or switch to Arimidex for five years.

By three years later, cancer was 64% less likely to recur in the group of women who switched to Arimidex, the study showed

Other Hormonal News

Those were not the only studies on the new hormonal treatments in 2003.

Yet another trial showed that women who took Arimidex instead of tamoxifen were slightly less likely to see their cancer recur after four years compared with those who took tamoxifen.

And in another study of nearly 300 women, those who took Arimidex were significantly more likely to become candidates for breast-conserving surgery than those who took standard tamoxifen, says Ian Smith, MD, of Royal Marsden Hospital in London.

And in the one trial that pitted Femara against Arimidex, those on Femara were slightly less likely to respond. But there was no difference in the amount of time it took for the cancer to grow.

Finally, the largest study ever to evaluate a hormonal therapy for women with advanced breast cancer showed that those on Femara stayed free of disease longer than those on tamoxifen.

A Gentler, Milder Drug?

As for side effects, the old standby drug tamoxifen is associated with a higher risk of uterine cancer than the newer aromatase inhibitors. But some studies have shown that women taking aromatase inhibitors are more prone to bone fractures than those taking tamoxifen.

But in general, side effects from aromatase inhibitors are mild, Goss says. Studies on the various aromatase inhibitors have shown that the drugs are generally tolerated about as well as placebo and any side effects appear to be mild. But one side effect in particular, increased bone loss, does concern doctors, but it has not been seen to be a problem in the short term.

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