Fulvestrant is approved for postmenopausal women with a certain type of breast cancer, called hormone receptor-positive metastatic breast cancer. If the cancer is not responsive to tamoxifen, then fulvestrant is an option. Fulvestrant is given once a month as a shot in the gluteal muscle.
Like the medication tamoxifen, fulvestrant is classified as anti-estrogen therapy. These drugs are designed to treat the forms of breast cancer that are sensitive to the hormone estrogen. In such cases, there are estrogen receptors on the outside of the breast cancer cells. These receptors take in estrogen, which stimulates their growth.
Each anti-estrogen drug works by a slightly different mechanism, making it possible for these drugs to be used in sequence. This means that doctors have more weapons to fight breast cancer, and they may be able to control the cancer for a longer period of time. Tamoxifen blocks estrogen from reaching the estrogen receptor in breast cancer cells. Fulvestrant blocks and destroys estrogen receptors in breast cancer cells.
The most common side effects include:
NauseaVomitingConstipationDiarrheaAbdominal painHeadacheBack painWeaknessHot flashesSore throat
You will not be able to take fulvestrant if you:
Are pregnant or breastfeedingAre allergic to any of the ingredients
Tell your doctor about any medications, including over-the-counter medications and herbs and supplements, before starting fulvestrant.
Faslodex (fulvestrant) injection. DailyMed website. Available at:
http://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=83d7a440-e904-4e36-afb5-cb02b1c919f7. Updated November 2012. Accessed October 6, 2014.
Tamoxifen. American Cancer Society website. Available at: http://www.cancer.org/treatment/treatmentsandsideeffects/guidetocancerdrugs/fulvestrant. Updated December 27, 2012. Accessed October 6, 2014.
Fulvestrant. EBSCO DynaMed website. Available at:
http://www.ebscohost.com/dynamed. Updated March 12, 2014. Accessed October 6, 2014.
Tamoxifen. American Cancer Society website. Available at: http://www.cancer.org/treatment/treatmentsandsideeffects/guidetocancerdrugs/tamoxifen. Updated February 11, 2010. Accessed October 6, 2014.
Last reviewed September 2014 by Michael Woods, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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