Zoladex is a type of hormonal therapy that is used in the treatment of prostate and breast cancers and some other conditions. This information is about Zoladex as a treatment for prostate cancer.

We have separate information about Zoladex for breast cancer.

Zoladex can be used alone or alongside other types of treatment. Your doctor will consider a number of different factors before deciding whether Zoladex is the most appropriate treatment for you.

Hormonal therapies interfere with the production or action of particular hormones in the body. Hormones are substances produced naturally in the body. They act as chemical messengers and help to control the activity of cells and organs.

Most prostate cancers need supplies of the hormone testosterone to grow. Production of testosterone by the testes is stimulated by a hormone called leuteinising hormone, which is produced by the pituitary gland.

Zoladex stops the production of leuteinising hormone by the pituitary gland. This reduces the production of testosterone in men. The cancer cells then grow more slowly or stop growing altogether. The cancer may shrink in size.

Zoladex is given by injection under the skin of the abdomen (subcutaneously). It is given as an injection every four weeks, or as a longer-acting preparation (every 12 weeks).

The injections can be given by your GP or practice nurse at the surgery. If you are not able to visit the surgery, a district nurse can give you the injection at home. Rarely, people may find the injection slightly uncomfortable and may notice an area of redness or darker colour at the injection site afterwards.

Each person's reaction to any medication is different. Many people have very few side effects with Zoladex, while others may experience more. We have outlined the most common side effects. However, we have not included those that are very rare and therefore extremely unlikely to affect you. If you notice any effects that you think may be due to the drug, but which are not listed here, please discuss them with your doctor or nurse.

You will see your doctor regularly while you have this treatment so that they can monitor the effects. This information should help you to discuss any queries about your treatment and its side effects with your doctor or nurse, who are in the best position to help and advise you.

Some people may have some of the following side effects:

Tumour flare There may be a temporary increase in the levels of testosterone for the first few days of Zoladex treatment. Because of this, you may find that you have an increase in symptoms over the first two weeks. You may experience an increase in bone pain or have problems passing urine. Other problems may occasionally occur due to a temporary increase in the size of the tumour. This is known as tumour flare. If you have any problems, you will need to let your doctor know. Other hormonal therapy drugs such as cyproterone acetate, flutamide or bicalutamide may be given for the first few weeks of starting Zoladex, to prevent tumour flare from occurring.

Hot flushes These can be quite common. Many men find that the hot flushes wear off after a period of time. There are a number of ways to help to reduce or control hot flushes and sweats. Some people find it is helpful to cut down on tea, coffee, nicotine and alcohol. Research shows that hormones called progestogens or some anti-depressants may be helpful in controlling hot flushes. Your nurse or hospital specialist can discuss this with you.

Some men find complementary therapies helpful. Your GP may be able to give you details about obtaining these on the NHS.

Sexual effects Loss of sex drive (libido) and erection difficulties (impotence) can occur. These effects often return to normal after stopping the drug. Some men may find that these problems carry on after treatment is over. Talk to your doctor if these effects are a problem as there are drugs which can be prescribed to help. Your doctor or nurse can discuss this with you.

Bone thinning (osteoporosis) You may be at more risk of this if you are taking Zoladex for longer periods of time. Your doctor can give you advice on how it can be monitored and treated, if needed. Let them know if you have any discomfort in your bones or joints.

Breast tenderness or fullness You may sometimes notice slight breast swelling and tenderness known as gynaecomastia. Your doctor can advise you about how this can be prevented or treated.

Skin rashes Some people experience skin rashes. Let your doctor know if this occurs.

Sore joints Some people may have soreness in their joints, but this is usually mild and will stop when the treatment is finished.

Weight gain and tiredness You may notice that you gain weight and feel less energetic than usual. This usually improves when hormonal treatment stops.

What if I miss an injection? Delaying an injection by a 2–3 days should not make a great difference, but it is important to remember that the benefits of the injections are designed to last either 4 or 12 weeks depending on which preparation you are prescribed, so you should have them as regularly as possible.

Length of treatment Your doctor will discuss the length of treatment that they feel is appropriate for your situation. It is often given for several months or even years. Zoladex is given for as long as it controls your cancer.

This section has been compiled using information from a number of reliable sources including:

• The electronic Medicines Compendium website www.medicines.org.uk (November 2008)
• Martindale: The Complete Drug Reference (35th edition). Sweetman et al. Pharmaceutical Press, 2007.
• British National Formulary (56th edition). British Medical Association and Royal Pharmaceutical Society of Great Britain, September 2008.

For further references, please see the general bibliography.