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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|.
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This information is about a hormonal therapy| used to treat prostate cancer| called diethylstilbestrol, which is also called Stilboestrol®. Throughout this information we refer to it by its more commonly used name, Stilboestrol.
This information should ideally be read with our general information about prostate cancer.
Stilboestrol is a man-made drug similar to the female hormone oestrogen. It is used in the treatment of advanced prostate cancer|, where the cancer has spread beyond the prostate gland - for example, to the bones|. 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 prostate cancers need supplies of the male hormone testosterone to grow. Testosterone is produced by the testes and the adrenal glands.
Stilboestrol reduces the level of testosterone in the body. It does this by making the brain think there are too many sex hormones circulating in the body. When this occurs, production of testosterone is 'switched off'. This reduced level of testosterone can help slow down the growth of the cancer cells and may cause the cancer to shrink in size.
Stilboestrol is a tablet that is taken once a day, ideally at the same time each day.
Your doctor will discuss with you the length of treatment that they feel is appropriate for your situation. Stilboestrol is often given for several months or even years. Treatment may continue for as long as it is effective in controlling your cancer.
Each person's reaction to any medicine is different. Many people have very few side effects with Stilboestrol, 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 below, discuss them with your doctor or nurse.
You may have some of the following side effects, to varying degrees:
Stilboestrol can increase the risk of getting a blood clot. Tell your doctor immediately if you have any pain, warmth, swelling or tenderness in an arm or leg, or any chest pain.
Some doctors may prescribe a low dose of aspirin while you are taking Stilboestrol to help prevent blood clots. It's important not to take drugs that contain aspirin unless they have been prescribed by your doctor.
Some people may have ankle swelling caused by fluid retention|. This is not harmful but can be uncomfortable. If you have ankle swelling, it may help to keep your legs elevated when sitting.
Some men may notice slight breast swelling and tenderness (also known as gynaecomastia). Your doctor can advise you about how this can be treated or prevented.
Loss of sex drive (libido) and erection difficulties (impotence) can occur in some men. These side effects may continue for as long as you are taking Stilboestrol, but they should improve if you stop taking the drug. Let your doctor know if you have any of these side effects, as they can prescribe medication to help.
You may feel tired| and lack energy while taking Stilboestrol.
This is usually mild and can be controlled. Nausea| can sometimes be relieved by taking the tablet with food. Let your doctor know if you have any of these side effects, as they can prescribe medicines to help.
Weight gain can be a side effect of Stilboestrol. This is often due to water retention, which is not harmful but can be uncomfortable.
Some people have headaches while taking Stilboestrol but this is not common. It is important to drink plenty of fluids. Let your doctor know if you have headaches as they can prescribe medicines to help.
Some men notice that their hair becomes thinner| while taking Stilboestrol. This is usually mild and the hair will grow back when treatment finishes.
Rarely, Stilboestrol can cause skin rashes and/or darkening of the skin.
Always let your doctor or nurse know about any side effects you have. There are usually ways in which they can be controlled or improved.
This information is based on our Diethylstilbestrol (Stilboestrol®) 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.