Classification: Estrogen Receptor Antagonist
About: Fulvestrant (Faslodex®)
Fulvestrant works by blocking estrogen receptors in breast tissue. While estrogen may not actually cause breast cancer, it is necessary for the cancer to grow in some breast cancers. With estrogen blocked, the cancer cells that feed off estrogen may not be able to survive. Fulvestrant is considered a pure anti-estrogen because it does not stimulate estrogen receptors outside of the breast tissue. Because of fulvestrant's unique ability, it offers an option for women who have shown resistance to tamoxifen or other hormonal therapy.
How to Take Fulvestrant
Fulvestrant is given by intramuscular (into a muscle) injection. In some cases it is necessary to give it in two injections due to the size of the dose.
Possible Side Effects of Fulvestrant
There are a number of things you can do to manage the side effects of fulvestrant. Talk to your care team about these recommendations. They can help you decide what will work best for you. These are some of the most common or important side effects:
Low Red Blood Cell Count (Anemia)
Your red blood cells are responsible for carrying oxygen to the tissues in your body. When the red cell count is low, you may feel tired or weak. You should let your oncology care team know if you experience any shortness of breath, difficulty breathing or pain in your chest. If the count gets too low, you may receive a blood transfusion.
Fatigue is very common during cancer treatment and is an overwhelming feeling of exhaustion that is not usually relieved by rest. While on cancer treatment, and for a period after, you may need to adjust your schedule to manage fatigue. Plan times to rest during the day and conserve energy for more important activities. Exercise can help combat fatigue; a simple daily walk with a friend can help. Talk to your healthcare team for helpful tips on dealing with this side effect.
Nausea and/or Vomiting
Talk to your oncology care team so they can prescribe medications to help you manage nausea and vomiting. In addition, dietary changes may help. Avoid things that may worsen the symptoms, such as heavy or greasy/fatty, spicy or acidic foods (lemons, tomatoes, oranges). Try saltines, or ginger ale to lessen symptoms.
Call your oncology care team if you are unable to keep fluids down for more than 12 hours or if you feel lightheaded or dizzy at any time.
Muscle, Bone or Joint Pain/Aches and Headache
Your healthcare provider can recommend medications and other strategies to help relieve pain.
Injection Site Reactions
You may have pain, redness, or swelling at the site of the injection. The injection can also cause nerve pain. Contact your care team if you experience any nerve pain.
There are a few things you can do to help with hot flashes. Several medications have been shown to help with symptoms, including clonidine (a blood pressure medication), low doses of certain antidepressants (such as venlafaxine and fluoxetine), and gabapentin. Talk to your healthcare team about these prescription products to determine if they are right for you.
Non-medical recommendations include:
- Keep well-hydrated with eight glasses of water daily.
- Drink ice water or apply an ice pack at the onset of a hot flash.
- Wear cotton or lightweight, breathable fabrics and dress in layers so you can adjust as needed.
- Exercise on a regular basis.
- Try practicing meditation or relaxation exercises to manage stress, which can be a trigger.
- Avoid triggers such as warm rooms, spicy foods, caffeinated beverages, and alcohol.
Less common, but important side effects can include:
- Diarrhea: Your oncology care team can recommend medications to relieve diarrhea. Also, try eating low-fiber, bland foods, such as white rice and boiled or baked chicken. Avoid raw fruits, vegetables, whole grain breads, cereals and seeds. Soluble fiber is found in some foods and absorbs fluid, which can help relieve diarrhea. Foods high in soluble fiber include: applesauce, bananas (ripe), canned fruit, orange sections, boiled potatoes, white rice, products made with white flour, oatmeal, cream of rice, cream of wheat, and farina. Drink 8-10 glasses on non-alcoholic, un-caffeinated fluid a day to prevent dehydration.
- Liver Toxicity: This medication can cause liver toxicity, which your oncology care team may monitor for using blood tests called liver function tests. Notify your healthcare provider if you notice yellowing of the skin or eyes, your urine appears dark or brown, or you have pain in your abdomen, as these can be signs of liver toxicity.
- Bleeding: This medication should be used with caution in patients with a history of bleeding disorders (including low platelets count) and/or patients on anticoagulant therapy; bleeding/hematoma may occur from the injection itself.
- Allergic Reactions: In some cases, patients can have an allergic reaction to this medication. Signs of a reaction can include: itching, hives, swelling of the face, lips, tongue, and throat, and trouble breathing. If you notice any changes in how you feel during the injection, let your nurse know immediately.
Exposure of an unborn child to this medication could cause birth defects, so you should not become pregnant while on this medication. Effective birth control is necessary during treatment and for 1 year after treatment. Even if your menstrual cycle stops, you could still be fertile and conceive. You should not breastfeed while receiving this medication or for 1 year after you have stopped taking it.