Breast Cancer Home > Fareston

If you have a type of breast cancer that is likely to grow in response to estrogen, your healthcare provider may prescribe Fareston. This medication works by binding to estrogen receptors on tumors, preventing them from growing. It comes as a tablet that is taken once daily. Side effects include nausea, sweating, and hot flushes.

What Is Fareston?

Fareston® (toremifene citrate) is a prescription medication approved to treat metastatic breast cancer in postmenopausal women who have estrogen receptor-positive or estrogen receptor-unknown tumors. Metastatic breast cancer is breast cancer that has spread beyond the breast to other areas of the body. Fareston belongs to a group of medicines known as selective estrogen receptor modulators (SERMs).
(Click Fareston Uses for more information on this topic, including possible off-label uses.)

Who Makes This Medication?

Fareston is made by Orion Oyj for ProStrakan, Inc.

How Does Fareston Work?

As mentioned, Fareston belongs to a group of medications called selective estrogen receptor modulators. SERMs work by binding to estrogen receptors in the body.
Estrogen receptors are slightly different in various areas of the body, and the effects of SERMs can therefore vary by body tissue. In some body tissues, SERMs bind to estrogen receptors and have estrogenic effects (they act like estrogen). In other body tissues, SERMs bind to estrogen receptors and have anti-estrogenic effects (they block the effects of estrogen).
Many breast cancers are estrogen sensitive, which means the tumor grows in response to estrogen. Breast cancer tumors that are sensitive to estrogen are known as estrogen receptor-positive tumors (or sometimes hormone receptor-positive tumors). They have estrogen receptors on their surface. When estrogen fits into these receptors, the tumor grows.
Fareston works to treat breast cancer because it has anti-estrogenic effects on breast tissue. When the drug binds to the estrogen receptors on estrogen receptor-positive tumors, it prevents estrogen from also binding. As a result, estrogen cannot make the tumor grow and cancer progression is slowed down.
Written by/reviewed by:
Last reviewed by: Kristi Monson, PharmD;
Last updated/reviewed:
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