Browser does not support script.
Skip to main content
search here
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 toremifene, which is also called Fareston®. Throughout this information we refer to it by its more commonly used name, toremifene.
This information should ideally be read with our general information about secondary breast cancer|.
Toremifene is a hormonal therapy used to treat women with breast cancer who have been through the menopause (change of life). It is used to treat women whose cancer has spread to other areas of the body (secondary breast cancer). 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. Hormones are substances produced naturally in the body. They act as chemical messengers and help control the activity of cells and organs.
The way toremifene works is not yet fully understood, but its main function is as an anti-oestrogen drug. This means that it interferes with the action of the female hormone oestrogen.
Many breast cancers rely on the sex hormone oestrogen to grow.
Hormone-sensitive breast cancers| have proteins called receptors on the breast cancer cells. They are known as 'oestrogen-receptor positive' (ER-positive) breast cancers. When oestrogen comes into contact with the receptors, it fits into them and stimulates the cancer cells to divide so that the tumour grows.
Toremifene fits into the oestrogen receptor and blocks oestrogen from reaching the cancer cells. This means the cancer either grows more slowly or stops growing altogether. Toremifene is most effective against ER-positive breast cancers.
Toremifene is a tablet that is taken once daily. It should be taken at approximately the same time each day.
Your doctors will discuss the length of treatment they feel is appropriate for your situation. Toremifene may be given for as long as it is effective in controlling your cancer.
Each person's reaction to any medicine is different. Some women have very few side effects while others may experience more.
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 are not listed here, discuss them with your doctor or nurse.
These are a common side effect of toremifene. They may gradually lessen over the first few months, but some women continue to have them for as long as they take toremifene.
There are a number of ways to help to reduce or control hot flushes and sweats. Some women find it helpful to avoid or cut down on tea, coffee, nicotine and alcohol.
Some drugs, including low doses of some antidepressants or the hormone progesterone, may be helpful in controlling this side effect. Your nurse or doctor can discuss this with you.
Some women may find complementary therapies help. 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 and menopausal symptoms|.
You may have some of the following side effects, to varying degrees:
Nausea| and indigestion| are fairly common but can often be relieved by taking your tablet with food or milk, or at night. Although nausea is quite common initially, it usually wears off after a few weeks.
Toremifene may sometimes cause tiredness, dizziness and a low mood. Tell your doctor if you have these symptoms.
Let your doctor know if you have any vaginal bleeding or discharge.
Blurred or reduced vision is uncommon but let your doctor know about any changes to your eyesight.
Women who are prescribed toremifene for cancer that has spread to the bones| may experience something called tumour flare when they start taking toremifene. This can cause a raised level of calcium in the blood (hypercalcaemia), with symptoms of nausea, vomiting and thirst. Occasionally, a short stay in hospital is needed until the calcium levels reduce.
This is very rare. Signs of a blood clot include pain, warmth, swelling or tenderness in an arm or leg, or chest pain. Tell your doctor immediately if you have any of these signs. Toremifene isn't usually given to people who have had a blood clot in the past.
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.
Studies have shown that women who take high doses of toremifene over a long period of time may have a very slightly increased risk of developing cancer of the lining of the womb (endometrial cancer|).
However, this small risk is generally outweighed by the benefits of taking toremifene. If detected early, treatment for endometrial cancer is usually very successful. An early warning sign is abnormal vaginal bleeding, although this is often caused by non-cancerous conditions such as polyps. If you have any abnormal vaginal bleeding, let your doctor know. Some women may have regular gynaecological check-ups.
This information is based on our Toremifene (Fareston®) 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.