Newer Drug Shows Better Survival Rates Than Tamoxifen For Postmenopausal Breast Cancer Patients

Main Category: Breast Cancer
Also Included In: Menopause
Article Date: 24 Aug 2009 - 0:00 PDT

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Postmenopausal women with breast cancer who are treated with the drug letrozole show increased survival rates after surgery compared with those treated with the drug tamoxifen, which is more widely used, according to a study published Thursday in the New England Journal of Medicine, HealthDay/U.S. News & World Report reports. According to HealthDay/U.S. News, both drugs are used to prevent the recurrence of breast cancer in postmenopausal women with hormone receptor-positive cancer by preventing the production or activity of estrogen. However, the drugs work differently, and it has been unclear whether one drug is better than the other. The study compared letrozol -- a newer, aromatase inhibitor drug that blocks the production of estrogen -- with tamoxifen, which is more widely used and interferes with estrogen rather than blocks its production.

The five-year study -- led by Alan Coates, co-chair of the scientific committee of the International Breast Cancer Study Group and a clinical professor at the University of Sydney's School of Public Health -- involved more than 8,000 postmenopausal women with hormone receptor-positive breast cancer. The women were randomly assigned to treatment with tamoxifen or letrozole for five years, with some of the women assigned to switch medications from letrozole to tamoxifen after two years.

The study also examined whether letrozole should be given before or after a period of tamoxifen treatment. The researchers "found that the differences were small, but that consistently in the higher-risk subgroups there was a benefit to starting with letrozole," Coates said. He noted that the difference in patients who switched medications after two years "was very small in all groups," adding that such findings "will be reassuring to those women who, having started adjuvant treatment with letrozole, are obliged for any reason to discontinue that drug. Our data suggest that they can safely switch to tamoxifen if required with little or no harm to their prognosis."

Victor Vogel, national vice president of research at the American Cancer Society, said that letrozole should be used for most patients because it is more effective and has fewer side effects than tamoxifen. However, he added that tamoxifen should be used by patients who have difficulty taking letrozole, which can cause joint and muscle aches in about 15% to 20% of patients (Reinberg, HealthDay/U.S. News & World Report, 8/19).

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