Oct. 21, 2011 -- Older women with early breast cancers are more likely to live longer and less likely to have the cancer come back when they take the drug Femara (letrozole) instead of tamoxifen, a long-term follow-up study shows.
At an average follow-up of more than eight years, postmenopausal women who took Femara for five years after surgery were 20% less likely to have their breast cancer return and 21% less likely to die from their breast cancer compared to postmenopausal women who took tamoxifen.
Femara is an aromatase inhibitor. Aromatase inhibitors are now generally considered the hormonal treatment first used by most postmenopausal early breast cancer patients whose tumors are fueled by estrogen, but not all women can take the drugs.
The drugs work by blocking the production of aromatase, which turns the hormone androgen into estrogen in the body. But because they don't stop the ovaries from making estrogen, they are not used to treat breast cancer patients who are still ovulating.
There are more than 2.6 million breast cancer survivors living in the U.S., according to the American Cancer Society.
About 230,000 new breast cancers are expected to be diagnosed in the U.S. this year and about 40,000 women will die of the disease.
The new updated analysis from the previously published Breast International Group (BIG) study adds to the evidence showing that aromatase inhibitors may be a more effective treatment than tamoxifen for postmenopausal women with estrogen-dependent tumors.
The study included just over 8,000 postmenopausal women living in 27 countries who had undergone surgery for cancers that had not spread beyond the breasts and lymph nodes.
One group of patients took either tamoxifen or Femara for five years. Another took tamoxifen for two years followed by three years of Femara or two years of Femara followed by three years of tamoxifen.
The study was originally funded by Femara manufacturer Novartis. But the drugmaker is no longer funding the continuing patient analysis, researcher Meredith M. Regan, ScD, tells WebMD.
With patient follow-up averaging more than eight years, daily treatment with Femara decreased relapse risk and death from breast cancer by about one-fifth, compared to treatment with tamoxifen.