The clinical trial has been halted early because of the positive results and researchers are notifying the 5,187 women worldwide who have participated in the study. Women on letrozole will continue taking the drug and those on the placebo can begin taking letrozole, if they wish.
Study researchers found that letrozole, when taken after five years of tamoxifen therapy, substantially increased the chance of remaining cancer free. In total, 132 women taking the placebo had their disease recur compared to 75 on letrozole. Overall, letrozole reduced the risk of recurrence by 43 percent so that after four years of participating in the trial, 13 percent of the women on the placebo, but only seven percent of those on letrozole had recurred. Deaths from breast cancer were also reduced. Seventeen women taking the placebo died of breast cancer compared to nine taking letrozole.
While tamoxifen is widely used to prevent breast cancer recurrence in post-menopausal women, it stops being effective after five years because, researchers believe, tumors become resistant to it.
"More than half of women who develop recurrent breast cancer do so more than five years after their original diagnosis," says Paul Goss, M.D., of Princess Margaret Hospital in Toronto. "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." Dr. G
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Contact: John Murphy
newsbureau@mayo.edu
507-284-5005
Mayo Clinic
9-Oct-2003