drugs that keep the adrenal glands from making estrogens. They are used to treat hormone-sensitive breast cancer in women after menopause. Examples include anastrozole (Arimidex®), letrozole (Femara®), and exemestane (Aromasin®). Aromatase inhibitors are being tested to find out if they can also be used to reduce breast cancer risk in women after menopause. See also chemoprevention, estrogen, hormone therapy, menopause.