This information is about a hormonal therapy called medroxyprogesterone acetate, which is commonly called Provera®. It is used to treat some types of cancer. The information should ideally be read with our general information that is appropriate to your situation.

Provera is a hormonal therapy that is used in the treatment of some cancers. It is a man-made drug that is similar to the female hormone progesterone. Hormones are substances that are produced naturally in the body. They act as chemical messengers and help to control the activity of cells and organs.

Provera is used in the treatment of breast cancer in post-menopausal women, cancer of the womb (endometrium) and occasionally prostate cancer. It may also be used to treat cancer of the kidney (hypernephroma).

The way Provera works is not yet fully understood, but it is thought that it interferes with the action of the female hormone oestrogen. Men produce small amounts of this hormone.

Many cancers rely on supplies of specific sex hormones, such as oestrogen, to grow. Cancer cells have proteins called receptors on their surface and the sex hormones can attach to the receptors.

Normally, when the oestrogen comes into contact with the receptors, it attaches to them and allows the cancer cells to divide so that the tumour grows.

Provera disrupts this process in some way. It may be that it prevents the cancer cells from maintaining the receptors on their surface. Alternatively, it may have a more direct way of destroying cancer cells that has not yet been identified.

Your doctor will consider a number of different factors before deciding whether Provera is the most appropriate treatment for you.

In breast cancer, Provera is mainly used as a treatment for women whose cancer has returned after a period during which it has been successfully controlled with other hormonal drugs, such as tamoxifen. Provera may also be used in women whose breast cancer has not responded to other hormonal therapies, but whose cancer has receptors for the sex hormone oestrogen on its surface.

In prostate cancer it may be used when the cancer has spread beyond the prostate gland, but other types of hormonal therapy are more commonly used in this situation.

In cancer of the womb (endometrium), Provera may be used if the cancer has spread outside the womb and cannot be completely removed with an operation, or if the cancer has come back after an operation.

In cancer of the kidney it may be used where the cancer cannot be completely removed with surgery, or if it has come back following an operation. This treatment may be used for both men and women who have kidney cancer.

Provera is a tablet. The tablets are available in three different strengths: 100mg, 200mg and 400mg. They are commonly taken once a day but can be prescribed in smaller doses to be taken at regular intervals during the day. When a single daily dose is prescribed it should be taken at approximately the same time each day – the actual time does not matter. When it is prescribed in divided doses (more than once per day) the doses should be evenly spaced throughout the day.

Each person's reaction to any medication is different. Many people who take Provera have no side effects while others may experience more. The side effects described in this information will not affect everyone. 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 which you think may be due to the drug, but are not listed in this information, 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, as they are in the best position to help and advise you. Very rarely, if the side effects are severe, you may have to stop taking the drug and a different hormonal therapy may be prescribed.

Some people may have the following side effects to varying degrees:

Increased appetite The most commonly reported side effect is an increase in appetite, causing some people to put on weight. Dieting may help to control this but you should consult your doctor or dietitian before making any changes to your diet. For people who have experienced weight loss as a result of their cancer this can be a beneficial effect.

Feeling sick (nausea) and indigestion Occasionally people feel sick (nauseated) for the first few weeks of taking Provera, but often the nausea then disappears. It can usually be relieved by medicines prescribed by your doctor, or by taking the tablets with food and milk.

Fluid retention Some people have experienced mild ankle swelling caused by fluid retention. This is not harmful but can be uncomfortable.

Vaginal bleeding in women Occasionally women may have some light vaginal bleeding (spotting) while having treatment with Provera. This is not harmful, although it may be a nuisance, but let your doctor know if it occurs.

When you stop taking the drug you are likely to bleed from the vagina in a way
which is similar to a 'period'.

Muscle cramps These are very rare, but can be uncomfortable. Let your doctor know if you have muscle cramps, as treatment can be prescribed to relieve them.

Skin rashes These are rare, but can occur.

Breast changes Women's breasts may feel tender and very rarely may produce small amounts of milk. This is not harmful but let your doctor know if it occurs.

Mood changes, tiredness and headaches Provera can cause nervousness, sleeplessness, drowsiness, tiredness, dizziness, low moods and headaches, but these effects are rare. Tell your doctor if they are a problem for you.

Like most drugs, Provera should not be taken during pregnancy. Even though women may find that their periods stop while taking Provera it is not a contraceptive. Reliable contraception must be used while having treatment with Provera.

People with diabetes will need to monitor their blood sugar more closely and may need to adjust their anti-diabetic medication while on treatment with Provera. They should contact their doctor if there are any problems with the control of their diabetes.

People who have had any form of blood clot should discuss this with their doctor before taking Provera, because it may increase the likelihood of clots.

Provera is often given to people who have lost weight due to their cancer, as it may help to stimulate appetite.

It can also be prescribed to reduce hot flushes in women during the menopause (change of life) and for men who have hot flushes as a result of treatment for prostate cancer.

It is sometimes used in small doses in the treatment of a variety of menstrual disorders.

Your doctor will discuss the length of treatment that they feel is appropriate for your situation. Provera is often given for several months or years. Treatment may continue as long as it is controlling the cancer.

Provera may interact with other medicines. Let your doctor know about any medications you are taking, including non-prescribed drugs such as complementary therapies and herbal drugs.

• Keep the tablets in a safe place where children cannot reach them, as Provera could harm them
• If your doctor decides to stop the treatment, return any remaining tablets to the pharmacist. Do not flush them down the toilet or throw them away
• Tell your doctor if you are sick just after taking the tablet, as you may need to take another one.
• If you forget to take your tablet, do not take a double dose. Let your doctor or nurse know. Don't worry – the levels of the drug in your blood will not change very much, but try not to miss more than one or two tablets in a row
• Remember to get a new prescription a few weeks before you run out of tablets. Make sure that you have plenty for holidays.

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

• Martindale: The Complete Drug Reference (35th edition). Sweetman et al. Pharmaceutical Press, 2007.
• British National Formulary (54th edition). British Medical Association and Royal Pharmaceutical Society of Great Britain, September 2007.

For further references, please see the general bibliography.