Exemestane (Aromasin ®)
This information is about a hormonal therapy used to treat breast cancer called exemestane, which is also called Aromasin ®. Throughout this information we refer to it by its more commonly used name, Aromasin.
This page describes Aromasin, how it is given and some of its possible side effects. It should ideally be read with our general information about breast cancer or secondary breast cancer.
Aromasin is a type of hormonal therapy used to treat breast cancer in women who have been through the menopause.
Hormones are substances produced naturally in the body. They act as chemical messengers and help control the activity of cells and organs. Hormonal therapies work by interfering with the production or action of particular hormones in the body.
You will see your doctor regularly while you have this treatment so they can monitor its effects. The information here should help you discuss any queries about your treatment and its side effects with your doctor or specialist nurse.
Some breast cancer cells have receptors, which allow particular types of hormones to attach to the cancer cell. Many breast cancers rely on the hormone oestrogen to grow. These cancers are known as oestrogen-receptor positive or ER-positive breast cancers. We have more information about different types of breast cancer.
In women who have had their menopause, the main source of oestrogen is through the conversion of androgens (sex hormones produced by the adrenal glands) into oestrogens. This is carried out by an enzyme called aromatase. The conversion process is known as aromatisation, and it happens mainly in the fatty tissues of the body.
Aromasin is a drug that blocks the process of aromatisation and reduces the amount of oestrogen in the body. As less oestrogen reaches the cancer cells, they grow more slowly or stop growing altogether. Drugs that work in this way are known as aromatase inhibitors. Other aromastase inhibitors include anastrozole (Arimidex ®) and letrozole (Femara ®).
Aromasin is a tablet that is taken once a day, preferably after a meal and at the same time each day. It doesn't matter whether this is in the morning or evening.
When Aromasin is given
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Your doctor will take a number of different factors into account when planning your treatment. Aromasin is used to treat oestrogen-receptor positive breast cancer in postmenopausal women.
Early breast cancer
Aromasin may be used to treat women with early breast cancer (cancer that has not spread) after they have completed two or three years of tamoxifen treatment.
Advanced breast cancer
Aromasin is used to treat women who have advanced or secondary breast cancer (cancer that has spread to other parts of the body). It is also used to treat women whose breast cancer has come back after initial treatment.
You might find it helpful to see our information about the staging and grading of breast cancer.
Your doctors will discuss with you the length of treatment they feel is appropriate for you. The length of your treatment will depend on your individual situation. Aromasin may be given over a number of years, or for as long as it is controlling the cancer. It may also be given after 2-3 years of treatment with tamoxifen.
Each person's reaction to any medicine is different. Most people have very few side effects with Aromasin, 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 here, discuss them with your doctor or nurse.
You may have some of the following side effects, to varying degrees:
Hot flushes and increased sweating
These effects are usually mild and may wear off after a period of time. Some people find it helps to cut down on tea, coffee, nicotine and alcohol. Research suggests that hormones called progestogens, or some antidepressants, may help control this side effect. Your doctor or nurse can discuss this with you.
Some people find complementary therapies such as acupuncture helpful. Your GP may be able to give you details about getting these on the NHS.
We have more information about breast cancer and menopausal symptoms.
Feeling sick (nausea)
Let your doctor know if this occurs, as it can usually be effectively treated. Feeling sick can often be relieved by taking your Aromasin tablet with food or at night.
Feeling tired (fatigue)
Some people find they are more tired when taking Aromasin. Getting plenty of rest should help. If you feel sleepy do not drive or operate machinery.
If you have frequent headaches your doctor can prescribe medicines to help.
Some women find they have trouble getting to sleep while taking Aromasin. You could try having a warm bath or a hot milky drink before bed, or using relaxation techniques, tapes or CDs.
Joint pains/muscular stiffness
Some women have pain and stiffness in their joints while taking Aromasin. Let your doctor know of these effects are a problem. You may find it helpful to take mild painkillers.
Abdominal pain and diarrhoea
Rarely, Aromasin can cause diarrhoea. This can usually be controlled with medicine, but let your doctor know if it is severe. It’s important to drink plenty of fluids if you have diarrhoea.
Risk of osteoporosis
Women who have, or are at risk of, osteoporosis (weakened bones) should have their bone strength assessed before and during treatment with Aromasin. Some women may need to take bone-strengthening drugs to help prevent osteoporosis developing.
We have more information on how you can keep your bones healthy.
Some women notice that some of their hair falls out while they are taking Aromasin. This is usually mild and the hair regrows at the end of treatment.
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.
Things to remember about Aromasin tablets
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Aromasin may interact with other medicines. Tell your doctor about any medication you are taking. This includes non-prescribed drugs such as complementary therapies, vitamins and herbal drugs.
Keep the tablets in a safe place, out of the reach of children.
If your doctor decides to stop the treatment, return any remaining tablets to the pharmacist. Don't flush them down the toilet or throw them away.
Don't worry if you forget to take your tablet. Do not take a double dose. 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 and make sure that you have plenty for holidays.
Avoid eating grapefruit and drinking grapefruit juice.
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If you’re admitted to hospital for a reason not related to the cancer, it’s important to tell the doctors and nurses looking after you that you are having hormonal treatment. You should tell them the name of your cancer specialist so that they can ask for advice.
It’s a good idea to know who you should contact if you have any problems or troublesome side effects when you’re at home.
This section has been compiled using information from a number of reliable sources, including:
British National Formulary. 63rd edition. 2012. British Medical Association and Royal Pharmaceutical Society of Great Britain.
Early and locally advanced breast cancer: diagnosis and treatment. February 2009. National Institute for Health and Clinical Excellence (NICE).
electronic Medicines Compendium (eMC). www.medicines.org.uk (accessed September 2012).
Sweetman, et al. Martindale: The Complete Drug Reference. 37th edition. 2011. Pharmaceutical Press.
Thank you to Bruce Burnett, Consultant Pharmacist, and the people affected by cancer who reviewed this information. Reviewing information is just one of the ways you could help when you join our Cancer Voices network.