Anastrozole is an aromatase inhibitor. This means that it blocks the enzyme aromatase (found in muscle, skin, breast and fat), which is used to convert androgens (hormones produced by the adrenal glands) into estrogens. Estrogen-dependent tumor cells grow smaller when estrogen is absent.
Hormones are chemicals produced by glands in the body that enter the bloodstream and can affect other parts of the body. For example, the hormone testosterone is produced in the testicles and is responsible for male characteristics such as a deeper voice and increased body hair. The use of hormone therapy to treat cancer is based on the observation that the growth of cancer cells may depend in part on the binding of hormones to receptors on the surface of cancer cells.
Hormone therapy can work by methods such as stopping the production of a particular hormone or disrupting the binding of a hormone to a cancer cell receptor. Different types of hormone therapy are categorized based on their function and/or the type of hormone affected.