Fulvestrant (Faslodex)

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1. What is fulvestrant?
2. How does fulvestrant work?
3. When might fulvestrant be prescribed?
4. How is fulvestrant given?
5. How long will I be given fulvestrant for?
6. What are the possible side effects of fulvestrant?
7. Blood clots
8. Can I take fulvestrant with other drugs?
9. Further support

1. What is fulvestrant?

Fulvestrant is a type of hormone therapy known as an oestrogen receptor down-regulator (see ‘How does fulvestrant work?’).

Fulvestrant is the generic (non-branded) name of the drug. Its brand name is Faslodex.

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2. How does fulvestrant work?

The hormone oestrogen can stimulate some breast cancers to grow.

Fulvestrant will only be prescribed if your breast cancer has receptors within the cell that bind to the hormone oestrogen, known as oestrogen receptor positive or ER+ breast cancer).

When oestrogen binds to these receptors, it can stimulate the cancer to grow. Fulvestrant works by blocking the action of oestrogen on the cancer cells. It binds to the oestrogen receptors, making them change shape and stop working. It also reduces the number of oestrogen receptors in the breast cancer cells. This is called down-regulation.

Oestrogen receptors are usually tested on primary breast cancers using tissue from a biopsy or after surgery. If you have secondary breast cancer your specialist 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.

If your cancer is oestrogen receptor negative, then fulvestrant will not be of any benefit to you.

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3. When might fulvestrant be prescribed?

Fulvestrant is used to treat breast cancer in women who have gone through the menopause (postmenopausal). It’s only suitable for women whose breast cancer is oestrogen receptor positive.

It may be given if your breast cancer has spread to the tissues and lymph nodes (glands) around the chest, neck and under the breastbone (known as locally advanced breast cancer or regional recurrence). It may also be used if you’ve been diagnosed with secondary breast cancer.

Fulvestrant may be prescribed if your breast cancer has progressed while you are taking, or after you have had, other hormone therapies. It can still work after other hormone therapies have stopped being effective because it acts in a different way.  

Occasionally it may be prescribed for premenopausal women in combination with other drugs, including a drug to stop the production of hormones in the ovaries (known as ovarian suppression). Your specialist team will discuss with you what they recommend and why.  

Fulvestrant is not routinely offered on the NHS. However, you may be given it as part of a clinical trial. Your specialist will be able to tell you if this is an option for you.

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4. How is fulvestrant given?

Fulvestrant is given by two injections, one in each buttock. These are known as intramuscular (IM) injections.

It’s usually given every two weeks for the first three doses, then once a month. It may be given either at the hospital or at your GP (local doctor) surgery.

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5. How long will I be given fulvestrant for?

You will usually be given fulvestrant for as long as it keeps your breast cancer under control. This will be assessed by scans and a review of how you are feeling and any symptoms. The length of time fulvestrant is taken for will vary from person to person and your specialist team will talk to you about your individual situation.

Find out more about how you will be monitored if you have secondary breast cancer.

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6. What are the possible side effects of fulvestrant?  

Most people having fulvestrant have mild side effects that often improve over time. However, everyone reacts differently to drugs and some people experience more side effects than others. The main side effects are listed here. You may have some or none of these.

If you have persistent side effects from fulvestrant, tell your specialist team so that they can decide how best to manage them.

Common side effects

As with most hormone therapies, you may have menopausal symptoms such as hot flushes or night sweats.

You may also experience:

  • temporary pain and inflammation around the injection site
  • nausea (feeling sick)
  • bone or joint pain
  • skin rashes

Fulvestrant can cause changes in your liver. This doesn’t usually cause any symptoms but your specialist team will ask you to have regular blood tests to check if your liver is working properly.

Less common side effects

Less common side effects include:

  • loss of appetite
  • vomiting
  • diarrhoea
  • general weakness or lack of energy
  • urine infections
  • constipation
  • headaches

Fulvestrant can reduce the number of platelets, which help the blood to clot. This may mean you bruise or bleed more easily. Tell someone in your specialist team if this happens.

Rare side effects include vaginal discharge or vaginal bleeding, which may occur in the first few weeks of treatment, usually after changing from another hormone therapy to fulvestrant. If you have vaginal bleeding at any time, tell someone in your specialist team.

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7. Blood clots

People with breast cancer have a higher risk of blood clots. Their risk is higher because of the cancer itself and some treatments for breast cancer. Having fulvestrant slightly increases the risk of blood clots such as deep vein thrombosis (DVT). People with a DVT are at risk of developing a pulmonary embolism. This is when part of the blood clot breaks away and travels to the lung.

Blood clots can be harmful but are treatable so it’s important to report symptoms as soon as possible.

If you experience any of the following symptoms contact your local A&E department, GP or specialist team straight away:

  • pain, redness/discolouration, heat and swelling of the calf, leg or thigh
  • shortness of breath
  • tightness in the chest
  • unexplained cough (may cough up blood)

Find out more about blood clots.

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8. Can I take fulvestrant with other drugs?

Always check with your specialist team if you’re taking any other medicines with fulvestrant.

You should not take drugs containing oestrogen, such as hormone replacement therapy (HRT), while you’re having fulvestrant.

As fulvestrant is given by injection, you need to tell your specialist if you’re taking any anti-coagulants (blood-thinning drugs).

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9. Further support

Your specialist team and breast care nurse can help with any questions you have. You can also call us free on 0808 800 6000 for information and support.

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Last reviewed: June 2018
Next planned review begins 2020

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