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Macmillan and Cancerbackup merged in 2008. Together we provide free, high quality information for people affected by cancer through our publications, website and phone service. Find out more|.
Find out how we produce our information|
This information is about a hormonal therapy| used to treat breast cancer called letrozole, which is also called Femara®. Throughout this information we refer to it by its more commonly used name, Femara.
This information should ideally be read with our general information about breast cancer| or secondary breast cancer|.
Femara is a type of hormonal therapy used to treat breast cancer| in women who have been the through menopause (change of life). You will see your doctor regularly while you have this treatment so they can monitor its effects.
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 control the activity of cells and organs.
Many breast cancers rely on the hormone oestrogen to grow. These cancers are known as hormone-sensitive breast cancers. 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 happens mainly in the fatty tissues of the body.
Femara is a drug that blocks the process of aromatisation and so 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 aromatase inhibitors include anastrozole (Arimidex®)| and exemestane (Aromasin®)|.
Femara is a tablet that is taken once a day, ideally at about the same time each day. It doesn't matter whether this is in the morning or the evening.
Femara is used to treat postmenopausal women with hormone-sensitive breast cancer.
Your doctor will take into account a number of different factors when planning your treatment.
Femara may be given to women with early breast cancer (cancer that hasn't spread) after they have had surgery| to remove the cancer. Giving treatment after surgery to reduce the risk of the cancer coming back is known as adjuvant therapy. Hormonal therapy is usually given for five years, but in some situations it may be given for longer.
Femara may sometimes be given to women after they have had five years treatment with another hormonal drug called tamoxifen|.
Sometimes Femara is given before surgery to women with localised early breast cancer, to allow them to have a lumpectomy (removal of the lump) rather than a mastectomy (removal of the breast). Giving treatment before surgery is known as neo-adjuvant therapy.
Femara may be used to treat women whose breast cancer has spread to other parts of the body (advanced or metastatic breast cancer). It can also be used to treat women whose cancer has come back after treatment with other hormonal therapies.
You might find it helpful to see our information about the staging and grading of breast cancer|.
Your doctors will discuss the length of treatment they feel is appropriate for your situation. Femara is often given over a period of years or for as long as it is effective in controlling your cancer, depending on your individual situation.
Each person's reaction to any medicine is different. Some people have very few side effects while others may experience more. The side effects described here will not 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 unlikely to affect you. If you notice any effects that are not listed here, discuss them with your doctor or nurse.
You may have some of the following side effects, to varying degrees:
These are usually mild and may wear off after a period of time. Some people find it helpful to cut down on tea, coffee, nicotine and alcohol. Research suggests that hormones called progestogens or some types of antidepressants may be helpful in controlling this side effect. Your nurse or doctor can discuss this with you.
Some people find complementary therapies|, such as acupuncture, helpful. Your GP may be able to give you details about having these on the NHS.
You can read more about treatments for menopausal symptoms like hot flushes in our information about breast cancer treatment and menopausal symptoms|.
This can usually be treated effectively, so let your doctor know if it occurs. Feelings of sickness| can often be relieved by taking your tablet with food or milk, or at night.
It's important to get enough rest. Let your doctor know if you are getting headaches, as medicines can be prescribed to help. You may find our information on fatigue| helpful.
Some women have pain and stiffness in their joints while taking Femara. Let your doctor know if these effects are a problem. You may find it helpful to take mild painkillers.
Some women notice that their hair| thins while taking Femara, but this is usually mild.
This may occur while using Femara. Gels that can help to overcome the dryness are available. These can be bought from a chemist or be prescribed by your doctor.
Women who have, or are at risk of, osteoporosis (weakened bones), should have their bones assessed before and during treatment with Femara. Some women may need to take bone-strengthening drugs to help prevent osteoporosis from developing.
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.
This information is based on our letrozole fact sheet and has been compiled using information from a number of reliable sources, including:
For answers, support or just a chat, call the Macmillan Support Line free (Monday to Friday, 9am-8pm)
If you have any questions about cancer, need support or just want someone to talk to, ask Macmillan.