Exemestane (
Aromasin®) is a prescription medication used to treat
breast cancer in postmenopausal women. Specifically, exemestane has been licensed to treat postmenopausal women who are switching from
tamoxifen (
Nolvadex®, Soltamox
®) and have:
- Early breast cancer that is hormone receptor-positive and have had surgery or radiation
- Advanced breast cancer that has not responded to tamoxifen.
Exemestane is made by Pfizer, Inc.
How Does Exemestane Work?
Exemestane is part of a group of medications called aromatase inhibitors. Aromatase is an enzyme found in various places in the body. These enzymes help produce estrogens (particularly, a certain estrogen called estradiol). In postmenopausal women, aromatase enzymes make most of the estrogen in the body. By blocking these enzymes, exemestane helps to decrease the amount of estrogen in the body.
Many breast cancers are sensitive to the estrogen hormone, meaning that the tumor grows with the help of estrogen. When a tumor is sensitive to estrogen, it has receptors on the outer surface of its cells. Estrogen fits into these receptors like a key opening a lock. When this connection is made, the cancer grows. Breast cancers that have estrogen (and/or progesterone) receptors are known as hormone receptor-positive tumors.