Study Tests New Drug Therapy for Breast Cancer Survivors

A new drug therapy is being tested for breast cancer survivors who have completed five years of tamoxifen, medication given to many patients to lessen the chances of a recurrence.

"Some studies suggest that taking tamoxifen beyond five years is not beneficial and could be harmful," said Dr. Richard Elledge, medical director of the Breast Care Center at Baylor College of Medicine and The Methodist Hospital. "We’re trying to look at other therapies that might be additionally useful beyond five years."

The drug being tested is exemestane.

Tamoxifen is an estrogen receptor blocker. Exemestane is an aromatase inactivator that selectively targets the aromatase enzyme, which is required to produce estrogen.

"Hormone therapy works in two ways. It can either block the receptor or lower the amount of estrogen that gets to the receptor. Exemestane lowers the amount of estrogen by blocking the enzyme," Dr. Elledge said.

The Breast Care Center is one of 100 sites conducting clinical trials to evaluate the drug in 3,000 postmenopausal women diagnosed with estrogen-receptor-positive breast cancer who have completed five years of tamoxifen.

"This is a way for women who have survived breast cancer to be proactive," Dr. Elledge said. "It allows us to do something besides monitoring after tamoxifen is completed."

In the trial, women who have completed five years of tamoxifen therapy are randomly assigned to take 25 milligrams of exemestane daily for two years, or a placebo. The most commonly reported side effects associated with exemestane include mild to moderate hot flashes, nausea and fatigue.

"Exemestane has been shown to be effective in women with advanced breast cancer," Dr. Elledge said. "This study will determine its effectiveness in women who have no evident breast cancer after five years of tamoxifen therapy."

The trial is under the direction of the National Surgical Adjuvant Breast and Bowel Project.

For further information, call the Breast Care Center at (713) 798-1986.

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©2006 Texas Medical Center

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