Fulvestrant

Fulvestrant is typically prescribed for postmenopausal women with hormone receptor-positive breast cancer that has become worse while taking other hormone treatments. It works by reducing the amount of estrogen, which can then decrease the cancer's growth. The medication is administered as an injection once a month. Potential side effects of fulvestrant include hot flashes, nausea, and weakness.

 

What Is Fulvestrant?

Fulvestrant (Faslodex®) is a prescription medication used to treat breast cancer in postmenopausal women. Specifically, fulvestrant has been licensed to treat postmenopausal women with hormone receptor-positive breast cancer that has worsened while taking another breast cancer hormone treatment.
 
(Click What Is Fulvestrant Used For? for more information, including possible off-label uses.)
 

Who Makes Fulvestrant?

Fulvestrant is made by AstraZeneca Pharmaceuticals.
 

How Does Fulvestrant Work?

Fulvestrant is a hormone treatment for breast cancer. It works in two ways. First, it works by binding to and blocking estrogen receptors. When fulvestrant binds to an estrogen receptor, it blocks estrogen hormones from binding to that receptor. Essentially, fulvestrant competes with the body's natural estrogen. However, unlike estrogen, the drug does not encourage breast cancer growth. Secondly, fulvestrant decreases the amount of estrogen receptors on the cells, which also reduces the effect of estrogen on breast cancer.
 
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, into which estrogen fits 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 the effects of estrogen, fulvestrant 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;