Exemestane (Aromasin)

Exemestane is also called Aromasin. It is a type of hormone therapy drug called an aromatase inhibitor, that is used to treat breast cancer.

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.

Although women past their menopause don’t produce oestrogen from their ovaries, they still produce a small amount by turning other sex hormones (androgens) into oestrogen. Androgens are made by your adrenal glands, the small glands above your kidneys. Androgens need an enzyme called aromatase to turn them into oestrogen. This change happens mainly in fatty tissue, muscle and the skin. Aromatase inhibitors stop (inhibit) aromatase, so it can’t change the androgen into oestrogen. These drugs are only suitable for women who've had their menopause.

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 gave you. Whether you have a full or empty stomach, for example, 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 click on search at the top of the page.

Many women have one or more of the following side effects

• Tiredness (fatigue) - this happens in about 1 in 5 women (20%)
• Feeling or being sick - this is usually mild and can be easily controlled by anti sickness tablets. It affects up to 1 in 5 women (20%)
• Hot flushes and sweats - this happens in about 1 out of 5 (20%) women

• Decreased interest in sex
• Painful joints - this happens in about 1 out of 10 women treated (10%)
• Skin rashes - these are usually mild. Let your doctor know if you have a rash. This happens in about 1 in 10 women taking exemestane (10%).
• Headaches - just over 1 in 10 of women (10%) have headaches when taking this treatment
• Insomnia - just over 1 in 10 women (10%) have some difficulty in sleeping
• Feeling dizzy - about 1 in 10 women (10%) have some dizziness
• Feeling low in mood, including depression
• Cough and breathlessness
• Loss of bone density - this is caused by a lack of oestrogen over a long period of time. When your bones are less dense they may break more easily. You should have a DEXA scan to check your bone density before you start treatment.
• Loss of appetite and indigestion
• Hair thinning
• Diarrhoea or constipation - if this happens it is usually mild. You should drink plenty of fluids. If you have diarrhoea and it becomes severe or persistent you could become dehydrated so tell your doctor or nurse.
• Vaginal bleeding - 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. This affects less than1 in 20 women treated (5%).

A few people may have blood pressure that is higher than usual during treatment. Your nurse or doctor will check this regularly.

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 other over the counter remedies - some drugs can react together.