Selective Estrogen Receptor Modulators (SERMs)

Selective estrogen receptor modulators (SERMs) are one of three types of hormonal therapy medicines used to treat estrogen receptor-positive breast cancer in women — both pre- and post-menopausal — and men.

There are three SERMs doctors use to treat breast cancer:

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  tamoxifen in pill form, also called tamoxifen citrate (brand name Nolvadex), and in liquid form (brand name: Soltamox)

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  Evista (chemical name: raloxifene)

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  Fareston (chemical name: toremifene)

SERMs block your body’s natural estrogen from binding with cancer cells in the breast. By cutting off the supply of estrogen, SERMs stop estrogen receptor-positive cancer from growing and spreading.

SERMS affect estrogen in two main ways:

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  They block the effects of estrogen in breast cells to stop breast cancer cells from multiplying.

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  They produce an estrogen-like effect in many other types of cells, including cells in the bones, liver, and uterus.

SERMs are called selective because they can work differently depending on the type of cell. Just as they can block estrogen in estrogen receptor-positive breast cancer, they can also turn on estrogen in bone, liver, or uterine cells, which is why doctors can use SERMs to treat various health conditions. For example, doctors use Osphena (chemical name: ospemifene) to treat vaginal dryness caused by menopause, as well as pain during sex. But ospemifene is not used to treat estrogen receptor-positive breast cancer.

Some of the most common side effects of SERMs include hot flashes, nausea, and vaginal discharge. Still, each SERM has a specific list of possible side effects, some of which are severe. It’s important to discuss possible side effects with your doctor.

It’s also important to let your doctor know if you have a history of blood clots or heart-related conditions — some SERMs may not be right for you if you do.

If you’re having problematic side effects from taking a SERM, tell your doctor right away. You may be able to take a different dose or try a different hormonal therapy medicine.

Learn more about the side effects of SERMs: tamoxifen, Evista, and Fareston.