Anastrozole is approved to treat certain types of breast cancer in postmenopausal women. In particular, the drug is used to treat breast cancer that is hormone receptor-positive or that has not responded to tamoxifen. The medication comes in tablet form, and is typically taken once a day. Potential side effects seen with anastrozole include hot flashes, nausea, and fatigue.
What Is Anastrozole?Anastrozole (Arimidex®) is a prescription medication used to treat breast cancer in postmenopausal women. Specifically, anastrozole has been licensed to treat postmenopausal women who have:
- Early breast cancer that is hormone receptor-positive
- Advanced or metastatic breast cancer that is either hormone receptor-positive or the hormone receptor status is not known
- Advanced breast cancer that has not responded to tamoxifen (Nolvadex®, Soltamox®).
(Click What Is Anastrozole Used For? for more information on what the drug is used for, including possible off-label uses.)
Who Makes Anastrozole?Brand-name anastrozole (sold under the name Arimidex) is made by AstraZeneca Pharmaceuticals. Generic versions are made by various manufacturers.
How Does Anastrozole Work?Anastrozole 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, most of the estrogen in the body is made by aromatase. By blocking these enzymes, anastrozole 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, anastrozole 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).