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Fareston (chemical name: toremifene) is approved by the U.S. Food and Drug Administration (FDA) to treat postmenopausal women diagnosed with advanced (metastatic) hormone-receptor-positive breast cancer.

Fareston is a pill that is taken once per day. Most doctors recommend taking Fareston at the same time every day.

Fareston won't work on hormone-receptor-negative breast cancer.

Fareston is not commonly used in the United States.

You should not take Fareston if you are breastfeeding, pregnant, trying to get pregnant, or if there is any chance that you could be pregnant. Fareston may cause damage to developing embryos. You should use an effective non-hormonal type of birth control — such as condoms, a diaphragm along with spermicide, or a non-hormonal I.U.D. — while you are taking Fareston. Ask your doctor which type of non-hormonal birth control would be best for you, as well as how long you should use this type of birth control after you stop taking Fareston.

Benefits of Fareston

Because Fareston is used to treat only metastatic breast cancer (breast cancer that has spread to other parts of the body), all of the studies on its benefits have been very small with relative short follow-up time. Still, the studies showed that Fareston was similar to tamoxifen in the time it stopped cancer from progressing.

Unlike tamoxifen, Fareston isn't affected by the CYP2D6 enzyme. The body uses the CYP2D6 enzyme to convert tamoxifen into its active form. Two things may interfere with the body’s ability to make this happen: a flaw in the CYP2D6 enzyme and certain medications that block the effectiveness of this enzyme. So Fareston may be a good option for anyone who has an abnormal version of the CYP2D6 enzyme or is taking another medicine that blocks CYP2D6 activity.

Side effects of Fareston

The most common side effects of Fareston are:

In some cases Fareston can cause a change in heart rhythm, which is serious. A change in heart rhythm can cause fainting, seizures, and may be life-threatening. You shouldn’t take Fareston if you were born with or have a history of irregular heartbeats or if you have low blood potassium levels or low blood magnesium levels that aren’t controlled with treatment.

Does insurance cover Fareston?

Costs for Fareston can vary. If you have health insurance, check with your insurance company to see if and how much of the cost of Fareston is covered. If you don't have health insurance or your insurance doesn't cover the cost of Fareston, ask your doctor or nurse about programs in your area that may be able to help.

Kyowa Kirin, the company that makes Fareston, offers financial assistance with its Patient Rx Solutions program.

You can also read the Paying for Your Care section for information on additional types of financial assistance and cost-lowering tips.

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