Exemestane

Exemestane is approved to treat certain types of breast cancer in postmenopausal women. By reducing the amount of estrogen the body produces, exemestane can help to decrease the growth of the breast cancer. The medication comes in the form of a tablet that is taken once a day. Prior to taking exemestane, be sure to tell your healthcare provider about any medical conditions you may have, as well as any medications you are taking. Some side effects of exemestane can include hot flashes, nausea, and fatigue.

 

What Is Exemestane?

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.
     
(Click What Is Exemestane Used For? for more information on what the drug is used for, including possible off-label uses.)
 

Who Makes Exemestane?

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.
 
By decreasing estrogen production, exemestane can help decrease the growth of these breast cancers. This type of breast cancer treatment is known as hormonal therapy (see Breast Cancer Hormone Treatment).
 
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Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD;