How they work

Aromatase inhibitors reduce the amount of estrogen in the body. This helps stop breast cancer cells from growing. Aromatase inhibitors are usually taken by mouth once daily for five years.

In the United States, three aromatase inhibitors are approved to treat breast cancer: anastrozole (Arimidex), exemestane (Aromasin) and letrozole (Femara).

These medicines are used to treat breast cancers that respond to estrogen or progesterone in people who have gone through menopause.