Study: Femara After Tamoxifen Cuts Risk of Breast Cancer Return

Breast cancer survivors who take tamoxifen for five years to prevent a recurrence can further cut the risk of a cancer return by then taking letrozole, according to a report published by the New England Journal of Medicine.

A study involving more than 5,000 post-menopausal women who had the most common form of early-stage breast cancer was halted early because of the surprisingly positive results for the women taking letrozole (Femara).

The researchers found that letrozole, when taken after five years of tamoxifen therapy, substantially increased the chance of a woman remaining cancer free.

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 a breast cancer recurrence.

Deaths from breast cancer were also reduced. Seventeen women taking the placebo died of breast cancer compared to nine taking letrozole.

"This very important advance in breast cancer treatment will improve the outlook for many thousands of women," said Dr. Andrew von Eschenbach, director of the National Cancer Institute. "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."

Estrogen fuels the growth of about half of all breast cancers, especially in older women. Tamoxifen is given to almost all such U.S. patients after surgery to help prevent breast tumors from returning.

But Tamoxifen it stops being effective after five years because, researchers believe, tumors become resistant to it. Letrozole works by limiting the ability of an enzyme called aromatase to produce estrogen.

Other Sources: New England Journal of Medicine