1. What is fulvestrant?
Fulvestrant is a type of hormone therapy used to treat breast cancer that has spread in women who have been through the menopause (postmenopausal).
It can sometimes be given to women who have not been through the menopause (premenopausal) and who are having .
You may hear it called by its brand name Faslodex.
2. How fulvestrant works
Some breast cancers use oestrogen in the body to help them to grow. These are known as oestrogen receptor positive or ER-positive breast cancers.
Hormone therapies block or stop the effect of oestrogen on breast cancer cells. Different hormone therapy drugs do this in different ways.
Breast cancers are tested to see if they are ER-positive using tissue from a biopsy or after surgery. If you have secondary breast cancer, your treatment team may discuss taking a sample of tissue from the site of the secondary breast cancer to retest the hormone receptors. This will depend on your individual situation.
3. Who might be offered fulvestrant?
You may be offered fulvestrant if you are postmenopausal and have:
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Locally advanced breast cancer (sometimes called regional recurrence) - breast cancer that has spread to the chest wall or skin of the breast, or lymph nodes around the chest, neck and under the breastbone but has not spread to other areas of the body. It cannot be removed by surgery
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Secondary (metastatic) breast cancer - breast cancer that has spread to other parts of the body
You may be given fulvestrant if breast cancer has progressed while you are taking, or after you have had, other hormone therapies such as letrozole or tamoxifen.
If you’re given fulvestrant and you’re premenopausal, you will also have a drug to stop your ovaries producing oestrogen (ovarian suppression). Your treatment team will talk to you about this.
Fulvestrant with targeted therapy
Fulvestrant may be given with another drug called a targeted therapy, such as abemaciclib, palbociclib, ribociclib or alpelisib.
You may be offered this if your breast cancer has not responded to treatment or has come back while you have been taking hormone therapy for primary breast cancer.
4. How is fulvestrant given?
Fulvestrant is given by 2 injections, 1 in each buttock. These are known as intramuscular injections.
Each injection is given slowly over 1 to 2 minutes.
You will have fulvestrant injections every 2 weeks for the first 3 doses, and then every 4 weeks.
You’ll have fulvestrant for as long as your treatment team feels you’re benefitting from the drug and any side effects are manageable.
5. Side effects of fulvestrant
Menopausal symptoms and breast cancer
Some breast cancer treatments, such as chemotherapy and hormone therapy, can cause menopausal symptoms. Find out more, including ways to cop...
Like any treatment, fulvestrant can cause side effects. Everyone reacts differently to drugs and some people have more side effects than others. These side effects can usually be managed and those described here will not affect everyone.
As fulvestrant can be given with a targeted therapy, it’s sometimes difficult to know which side effects are being caused by which treatment.
If you’re worried about any side effects, regardless of whether they’re listed here, talk to your chemotherapy nurse or treatment team.
Common side effects
Extreme tiredness (fatigue)
Fatigue is extreme tiredness that does not go away with rest or sleep. It’s a common side effect of fulvestrant.
If you think you have fatigue, tell your GP or treatment team. They can assess you and offer advice on how to manage your energy levels.
Find out more about managing fatigue.
Menopausal symptoms
Menopausal symptoms include:
- Hot flushes
- Night sweats
- Vaginal dryness
- A decrease in sex drive (libido)
Find out more about managing menopausal symptoms.
Other common side effects
You may also have:
- Temporary pain and swelling around the injection site
- Feeling sick (nausea)
- Bone or joint pain
- Skin rashes
Fulvestrant can cause changes in your liver. This doesn’t usually cause any symptoms, but you will have regular blood tests to check if your liver is working properly.
Less common side effects
Less common side effects include:
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Loss of appetite
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Being sick (vomiting)
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Diarrhoea
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Urine infections
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Headaches
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Numbness and tingling in hands or feet (peripheral neuropathy)
Fulvestrant can reduce the number of platelets in your blood. These help the blood to clot. This may mean you bruise or bleed more easily. Tell your treatment team if this happens.
Rare side effects
Rare side effects of fulvestrant include vaginal discharge or vaginal bleeding. This may occur in the first few weeks of treatment, usually after changing from another hormone therapy to fulvestrant.
If you have vaginal bleeding or discharge at any time, tell your treatment team.
6. Other important information
Blood clots
People with breast cancer have a higher risk of blood clots. Having fulvestrant also increases the risk of blood clots such as a DVT (deep vein thrombosis).
If you have a DVT, there’s a risk part of the blood clot could break away and travel to the lung. This is known as a pulmonary embolism (PE).
Blood clots can be life-threatening and should be treated quickly.
Blood clot symptoms
Contact your treatment team or go to your local A&E department straight away if you have any of the following symptoms:
- Pain, redness/discolouration of the skin, heat and swelling of the arm or leg
- Swelling, redness or tenderness where a central line is inserted to give chemotherapy, for example in the arm, chest area or up into the neck
- Shortness of breath
- Pain or tightness in the chest
- Unexplained cough or coughing up blood
Find out more about blood clots.
Life during treatment
Going through breast cancer treatment can affect you physically and emotionally. Read our tips to help you cope.
Travel and vaccinations
If you’re planning a holiday or need to travel overseas, check with your treatment team first.
You should not have any live vaccines while you’re having chemotherapy or targeted therapies.
Live vaccines include:
- Mumps
- Measles
- Rubella (German measles)
- Polio
- BCG (tuberculosis)
- Yellow fever
Live vaccines contain a small amount of live virus or bacteria. If you have a weakened immune system, which you may do during treatment, they could be harmful.
Talk to your GP or treatment team before having any vaccinations.
If anyone you have close contact with needs to have a live vaccine, speak to your treatment team or GP. They can advise what precautions you may need to take depending on the vaccination.
COVID-19 vaccination
If you’re having chemotherapy or targeted therapies, you’re advised to speak to your treatment team about the best time to have a COVID-19 vaccination.
Flu vaccination
Anyone at risk of a weakened immune system, and therefore more prone to infection, should have the flu vaccine. This includes people due to have, or already having, chemotherapy.
The flu vaccine is not a live vaccine so does not contain any active viruses.
Talk to your treatment team or breast care nurse about the best time to have your flu vaccine.
Allergic reaction
Having an allergic reaction to fulvestrant is rare.
If you do have an allergic reaction, it’s more likely to happen within the first few minutes of your first or second treatment.
You’ll be monitored closely so any reaction can be dealt with immediately.
Symptoms of an allergic reaction include:
- Flushing
- Skin rash
- Itching
- Back pain
- Shortness of breath
- Faintness
- High temperature or chills
If you have a severe reaction, treatment will be stopped immediately.
If you have a less severe reaction, you may need to take medication before future treatments to reduce the risk of further reactions.
Can I take fulvestrant with other drugs?
As fulvestrant is given by injection, you need to tell your treatment team if you’re taking any blood-thinning drugs.
If you’re taking any other prescribed or over-the-counter medicines, let your treatment team know.
Ask your treatment team before taking any herbal medicines or supplements.
Sex and contraception
You’re advised not to become pregnant while you’re having fulvestrant. This is because the drug could harm a developing baby.
You can still become pregnant even if your periods have stopped with ovarian suppression or have become irregular. If you’re sexually active with a chance of becoming pregnant, your treatment team is likely to advise you to use a non-hormonal method of contraception, such as condoms and Femidoms, while taking fulvestrant.
It may also be possible to use a coil (IUD or intrauterine device). However, you would need to discuss this with your treatment team as not all types are suitable for women with breast cancer.
If you think you may be pregnant, stop fulvestrant and tell your treatment team as soon as possible.
Fertility
We don’t fully know the impact of fulvestrant on fertility.
If you were diagnosed with locally advanced or secondary breast cancer before you started or completed a family, you may be concerned about your fertility.
Getting pregnant while taking fulvestrant for breast cancer treatment is not recommended. You can talk to your treatment team about any possible fertility preservation options before starting treatment.
Breastfeeding
You’ll be advised not to breastfeed during treatment. This is because there’s a chance the drug could be passed on through breast milk.
7. Further support
Your treatment team and breast care nurse can help with any questions you have. You can also call us free on our helpline for information and support.
On our online forum, you can find people going through treatment at the same time as you.
