Exemestane (Aromasin)

Exemestane is also called Aromasin. It is a type of hormone therapy drug called an aromatase inhibitor and is used to treat breast cancer.It is only suitable for women who've had their menopause.

Many breast cancers are stimulated to grow by the female sex hormones oestrogen and progesterone. These breast cancers are called hormone sensitive or hormone receptor positive and can be treated with drugs that block the effects of these hormones.

In women who have had their menopause, oestrogen is mainly produced by changing androgens (sex hormones produced by the adrenal glands) into oestrogens. This process is called aromatisation and happens mainly in the fatty tissues, muscle and the skin. It needs a particular enzyme called aromatase.

Exemestane blocks the process of aromatisation. So it lowers the amount of oestrogen in the body. In early breast cancer, taking exemestane can help to stop breast cancer coming back. In advanced breast cancer the cancer cells may grow more slowly or stop growing completely.

You take exemestane as a tablet, once a day after food. There is general information about hormone therapies in the cancer treatment section.

It is very important that you take tablets according to the instructions your doctor or pharmacist gives you. For example, whether you have a full or empty stomach can affect how much of a drug gets into your bloodstream. You should take the right dose, not more or less. And never stop taking a cancer drug without talking to your specialist first.

We've listed the side effects associated with exemestane below. You can use the links to find out more about each side effect. Where there is no link, please go to our cancer drug side effects section or click on search at the top of the page.

More than 10 in every 100 people have one or more of these.

• Hot flushes and sweats – this happens in more than 1 in 5 women (22%)
• Painful joints or muscles – this happens in just under 1 in 5 women (18%)
• Tiredness (fatigue) – this happens in about 1 in 6 women (16%)
• Feeling or being sick – this is usually mild and can be easily controlled by anti sickness tablets. It affects more than 1 in 10 women (12%)
• Difficulty sleeping (insomnia) – more than 1 in 10 women have this
• Hair thinning affects more than 1 in 10 women

Between 1 and 10 in every 100 people have one or more of these.

• Loss of appetite and indigestion
• Lowered interest in sex
• Skin rashes – these are usually mild. Let your doctor or nurse know if you have a rash. This happens in about 1 in 10 women taking exemestane (10%)
• Headaches – about 1 in 10 women (10%) have headaches when taking this treatment
• Feeling dizzy – about 1 in 10 women (10%) have some dizziness
• Feeling low in mood, including depression
• A cough and breathlessness
• Loss of bone strength – this is caused by a lack of oestrogen over a long period of time and bones may break more easily. You should have a DEXA scan to check your bone density before you start treatment
• Diarrhoea or constipation – if this happens it is usually mild. You should drink plenty of fluids.
• Vaginal bleeding occurs in less than 1 in 20 women (5%) – this mainly happens during the first few weeks of treatment when women have changed from one type of hormone therapy to another. Tell your doctor or nurse if the bleeding continues
• Swelling in the hands and feet caused by a build up of fluid

The side effects above may be mild or more severe. A side effect may get better or worse through your course of treatment, or more side effects may develop as the course goes on. This depends on

• How many times you've had the drug before
• Your general health
• The amount of the drug you have (the dose)
• Other drugs you are having

Talk to your doctor, pharmacist or nurse about all your side effects so that they can help you manage them. You should have a contact number for your chemotherapy nurse, clinic or ward nurse. You can ring if you have any questions or problems. They can give you advice or reassure you. If in doubt, call them.

Tell your doctor about any other medicines you are taking, including vitamins, herbal supplements and over the counter remedies – some drugs can react together.