Research Area: Endocrinology Biological Activity: Anastrozole inhibits the enzyme aromatase, which is responsible for converting androgens to estrogens. Anastrozole binds reversibly to the aromatase enzyme through competitive inhibition.[1] Elevated levels of estrogens may increase the severity of breast cancer, as sex hormones can cause hyperplasia and differentiation at estrogen receptor sites.[1] Anastrozole is used to treat breast cancer after surgery and for metastases in post-menopausal women.[1]