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Breast Cancer Drug Femara Beats Tamoxifen

Jan. 27, 2005 -- Postmenopausal women with early breast cancer have fewer recurrences after surgery when they take Femara instead of tamoxifen, new research shows.

The results were announced at the Primary Therapy of Early Breast Cancer 9th International Conference in Switzerland. Femara's maker, Novartis, funded the study. Novartis is a WebMD sponsor.

The study posed a key question: Which drug is better at reducing the risk of breast cancer's return in postmenopausal women who have had breast cancer surgery?

Survival More Common

The issue affects thousands of women. It's becoming more common to survive breast cancer.

There are more than 2 million U.S. women who are breast cancer survivors, says the American Cancer Society (ACS).

This year, more than 211,000 U.S. women will be diagnosed with breast cancer, the ACS estimates. About 40,000 will die of the disease. For survivors, keeping cancer at bay is a top priority.

Drugmaker's Study

More than 8,000 women in 27 countries participated in the study. All had undergone breast cancer surgery and were postmenopausal. Their breast cancer was treated early; it hadn't spread beyond the breast and lymph nodes.

The women's tumors were dependent on the hormone estrogen to grow. About two-thirds of breast cancers are fueled by estrogen, says the ACS.

Typically, women take tamoxifen for about five years. About 500,000 U.S. women take tamoxifen and 80,000 join their ranks each year.

How the Drugs Work

Femara and tamoxifen both lower the amount of estrogen in the body, slowing the growth of estrogen-dependent tumors. But they work differently.

Tamoxifen blocks estrogen receptors. It's the standard treatment for postmenopausal women with estrogen-dependent tumors. Tamoxifen was a major breakthrough when it debuted more than 25 years ago. It's also used to prevent breast cancer in women at high risk for the disease.

Femara takes a different approach. It's the second in a newer class of breast cancer drugs called aromatase inhibitors.

Aromatase inhibitors target aromatase, which is needed to turn male-type hormones called androgens into estrogen. Thwarting aromatase prevents androgens from morphing into estrogen. As a result, estrogen levels are lower.

More than 8,000 women in 27 countries participated in the study. All had undergone breast cancer surgery and were postmenopausal. Their breast cancer was treated early; it hadn't spread beyond the breast and lymph nodes.

The women's tumors were dependent on the hormone estrogen to grow. About two-thirds of breast cancers are fueled by estrogen, says the ACS.

Typically, women take tamoxifen for about five years. About 500,000 U.S. women take tamoxifen and 80,000 join their ranks each year.