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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.

Aromasin Helps Prevent Cancer Recurrence continued...

"The extent of risk reduction surprised us," Coombes tells WebMD. "It indicates a fair number of people become resistant to tamoxifen two to three years after they start taking it."

Several smaller trials showed that Aromasin may also be effective for the treatment of hormone-responsive metastatic breast cancer. In one study, 122 women who had received no prior hormone therapy were randomly assigned to get tamoxifen or Aromasin. Disease stabilized for at least six months in 57% of those on Aromasin vs. 42% on tamoxifen.

And in a study of 105 women who had previously been on aromatase inhibitors, about one-fourth appeared to benefit from the newer drug.

Aromasin appears to be useful for in women whose breast cancers failed to respond to aromatase inhibitors like Arimidex or Femara, says co-investigator David Cameron, MD, a medical oncologist at Western General Hospital in Edinburgh, Scotland.

Three in Five Breast Cancers Fueled by Estrogen

Breast cancer is the second biggest cancer killer of women in the industrialized world, taking the lives of about 40,000 women each year in the U.S. alone. More than 211,000 new cases will be diagnosed.

About three in five of these women have tumors that are fueled by the hormone estrogen, making hormone therapy to stop this growth a cornerstone of regimens to prevent recurrences and improve survival.

While tamoxifen prevents estrogen from acting on tumors, aromatase inhibitors actually block an enzyme the body uses to make estrogen, thereby slashing the body's production of estrogen altogether.

The new studies suggest that this different mechanism of action to decrease estrogen levels may mean that aromatase inhibitors may shrink tumors better and longer with fewer side effects, doctors say.

Femara Study Halted Early

Goss says the drug was so effective that an international committee decided to disclose the results early in order to offer the drug to all women in the trial.

The international trial pitted Femara against placebo in nearly 5,200 women following five years of tamoxifen therapy. Four years after the start of the study, cancer came back in 13% of the women on placebo but only in 7% of those on Femara.

Anderson, who as a patient of Goss was invited to participate in the study, tells WebMD that the day the trial was stopped early was "very exciting. I found out I had been on Femara for the last two years, indicating to me that my chances of recurrence had been cut in half."

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