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Macmillan and Cancerbackup merged in 2008. Together we provide free, high quality information for people affected by cancer through our publications, website and phone service. Find out more|.
Find out how we produce our information|
This information is about a hormonal therapy| used to treat breast cancer| called fulvestrant, which is also called Faslodex®. Throughout this information we refer to it by its more commonly used name, Faslodex.
This information should ideally be read with our general information about breast cancer or secondary breast cancer|.
Faslodex is a type of hormonal therapy. It is used to treat breast cancer that has spread in women who have had their menopause (change of life). Faslodex is usually used when other hormonal therapies are no longer controlling the cancer. You will see your doctor regularly while you have this treatment so they can monitor its effects.
Hormonal therapies interfere with the production or action of particular hormones. Hormones are substances produced naturally in the body. They act as chemical messengers and help control the activity of cells and organs.
Many breast cancers rely on the female sex hormone oestrogen to grow. Some breast cancer cells contain proteins called oestrogen receptors.
Hormone-sensitive breast cancers| have proteins called receptors on the breast cancer cells. They are known as 'oestrogen-receptor positive' (ER-positive) breast cancers. When oestrogen comes into contact with the receptors, it fits into them and stimulates the cancer cells to divide so that the tumour grows.
Faslodex works in two ways. It is an anti-oestrogen drug. It fits into the oestrogen receptor and blocks oestrogen from reaching the cancer cells. This means the cancer either grows more slowly or stops growing altogether. It also works by reducing the number of receptors on breast cancer cells.
Faslodex is given as an injection every four weeks directly into the muscle of the buttock. You usually have an additional injection two weeks after the first dose.
It can be given by your GP or practice nurse at the surgery. If you're not able to visit the surgery, a district nurse can give you the injection at home.
You may find the injection slightly uncomfortable and may notice an area of redness at the injection site afterwards.
Faslodex is used to treat women with ER-positive secondary (metastatic) breast cancer. It can be given to post-menopausal women who have been treated with another hormonal therapy but whose cancer has progressed.
Your doctors will discuss with you the length of treatment they feel is appropriate for your situation. Faslodex may be given for months or longer.
Each person's reaction to any medicine is different. Many people have very few side effects with Faslodex, while others may experience more. The side effects described here won't affect everyone and may be different if you are having more than one drug.
We have outlined the most common side effects but haven't included those that are rare and therefore unlikely to affect you. If you notice any effects that aren't listed in this information, discuss them with your doctor or nurse.
You may have some of the following side effects, to varying degrees:
Nausea, vomiting| and diarrhoea| are rare side effects. If they do occur let your doctor know, as they can usually be treated. If you get diarrhoea, it's important to drink plenty of fluids.
These effects are usually mild and may wear off after a period of time. Sometimes women find that avoiding or cutting down on tea, coffee, nicotine and alcohol can reduce sweats. Research suggests that hormones called progestogens or some types of antidepressants may help to control this side effect. Your doctor or nurse can discuss this with you.
Some people find complementary therapies|, such as acupuncture, helpful. Your GP may be able to give you details about obtaining these on the NHS.
You can read more about treatments for menopausal symptoms like hot flushes on our page about managing menopausal symptoms|.
Let your doctor know if you are getting headaches, as they can prescribe medication to help.
Some women experience pain and stiffness in their joints. Let your doctor know if these effects are a problem. You may find it helpeful to take mild painkillers.
Some people have mild skin rashes.
Vaginal bleeding has been reported, usually in the first few weeks of treatment. This is rare and usually occurs after changing from another hormonal therapy to treatment with Faslodex. If bleeding continues, tell your doctor or breast care nurse.
You may have some pain and inflammation at the injection site. Let your doctor know if this becomes troublesome.
Faslodex can slightly increase the risk of blood clots. Tell your doctor immediately if you have pain, warmth, swelling or tenderness in an arm or leg, or any chest pain.
Because Faslodex is given by injection into a muscle, it shouldn't be used in people with certain blood disorders or who are receiving blood thinners (anticoagulants), such as warfarin.
Always let your doctor or nurse know about any side effects you have, as there are usually ways in which they can be controlled or improved.
Missing an injection by two days or so shouldn't make a great difference. However, it is important to remember that the injections are designed to last for four weeks, so you should have them as regularly as possible.
This information is based on our Fulvestrant (Faslodex®) fact sheet and has been compiled using information from a number of reliable sources, including:
For answers, support or just a chat, call the Macmillan Support Line free (Monday to Friday, 9am-8pm)
If you have any questions about cancer, need support or just want someone to talk to, ask Macmillan.