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A landmark study finds that the drug Femara (generic name, letrozole) significantly improves the chances of breast cancer survival when taken after five years of treatment with the drug tamoxifen (brand name, Nolvadex). The research—which was halted early to allow women in the study who were taking a placebo, or inactive pill, to reap the benefits of Femara—found that taking Femara after tamoxifen reduced the risk of a recurrence and death from breast cancer by nearly one half. The U.S. National Cancer Institute is encouraging breast cancer patients to discuss the possibility of taking Femara after five years of treatment with tamoxifen. To conduct their study, Paul E. Goss, MD, PhD, of Princess Margaret Hospital in Toronto, and his colleagues enrolled a total of 5,187 women from Canada, the United States, England, Belgium, Ireland, Italy, Poland, Portugal and Switzerland. The goal of the study was to test the effectiveness of Femara after five years of treatment with tamoxifen. Tamoxifen has been used for over 20 years to treat advanced breast cancer, and in 1998, it became the first drug approved by the U.S. Food and Drug Administration (FDA) to help prevent breast cancer in women at high risk of the disease. Research has shown that taking tamoxifen for five years after other breast cancer treatments (such as surgery and radiation) helps reduce the chance of a cancer recurrence, but the benefit does not continue beyond five years of use before tumors become resistant to the drug. In their study, Dr. Goss and his team found that taking Femara after five years of tamoxifen significantly reduces the changes of a recurrence (return) of breast cancer. Only 75 women taking Femara experienced a breast cancer recurrence in the study, compared to 132 women who were given a placebo (inactive pill). After four years of the study, only 7% of women taking Femara experienced a breast cancer recurrence, compared to 13% of women taking a placebo. "This very important advance in breast cancer treatment will improve the outlook for many thousands of women," said Andrew von Eschenbach, MD, Director of the National Cancer Institute (NCI), in an NCI news release. "This is one more example of the ability to interrupt the progression of a cancer using a drug that blocks a crucial metabolic pathway in the tumor cell." The study also showed that taking Femara after five years of tamoxifen reduces deaths from breast cancer. A total of 17 women taking a placebo died in the study, compared to 9 women taking Femara. The way in which Femara and tamoxifen fight breast cancer is different. To grow and reproduce, breast cancer cells require the female hormone estrogen. Tamoxifen is an "anti-estrogen" and works by blocking estrogen from breast cancer cells, thereby "starving" cancer cells. On the other hand, Femara works by reducing the total amount of estrogen in the body (circulating estrogen levels), thereby limiting the amount of estrogen that can affect breast cancer cells. "More than half of women who develop recurrent breast cancer do so more than five years after their original diagnosis," said Dr. Goss, in an NCI news release. "For years, we have thought that we had reached the limit of what we could do to reduce the risk of recurrence with five years of tamoxifen. Our study ushers in a new era of hope by cutting these ongoing recurrences and deaths from breast cancer after tamoxifen by almost one half." The researchers say that all women who are taking tamoxifen as part of their breast cancer treatment should talk with their physicians about beginning Femara after five years to further reduce the risk that there cancer might return. "This large trial only began in 1998 and we already have important results that will change clinical practice," says Jeffrey Abrams, MD, Coordinator of the National Cancer Institute's Cooperative Group breast cancer treatment trials, in an NCI news release. "This is a tribute to the patients and physicians who participated since their efforts will now have a positive impact on so many lives."
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