Aromatase inhibitors are drugs that work by binding to the body’s aromastase enzyme, which is responsible for producing estrogen. Many breast cancer cells depend on estrogen to grow and multiply quickly. Once the aromatase inhibitor binds to the aromastase enzyme, the bound aromatase enzyme can no longer produce estrogen. This drug-caused lack of estrogen “starves” estrogen-dependent breast cancer cells, preventing them from multiplying.
Several aromatase inhibitors are used to help treat advanced breast cancer, including:
• Aromasin (generic name, exemestane)
• Femara (generic name, letrozole)
• Arimidex (generic name, anastrozole)
A recent, large international trial of more than 8,000 post-menopausal women treated for ER-positive breast cancer showed that Femara (generic name, letrozole):
• Lowered the risk of relapse (recurrence) by 19%
• Lowered the risk of distant recurrence by 27%
If a woman who has had estrogen receptor-positive (ER-positive) breast cancer (with or without lymph node involvement) has been taking tamoxifen for 5 years, it generally is recommended that she consider taking an aromatase inhibitor.
1. New England Journal of Medicine. 12/29/05.