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Breast cancer hormone therapy side effects

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This page tells you about the side effects of hormone therapy for breast cancer. There is information about

 

A quick guide to what's on this page

Breast cancer hormone therapy side effects

Hormone therapy for early breast cancer affects people differently. Some people have more side effects than others. Many women find that the side effects are worse at the start of treatment. They usually settle down after a few weeks or months.

Some side effects are common to most hormone therapies used to treat breast cancer. These include hot flushes, changes to your periods, less interest in sex, vaginal dryness, feeling sick, painful joints, mood changes, and tiredness.

Possible longer term side effects

There are a few possible longer term side effects of hormone treatments. Drugs called aromatase inhibitors can cause bone thinning. This can make you more likely to break a bone. You will probably have tests to check the strength of your bones (bone density) before you start treatment. Your doctor may also give you calcium and vitamin D supplements to help lessen the effect on your bones.

If you are taking tamoxifen, there is a very small risk of developing cancer of the womb. If you have any abnormal bleeding you should see your doctor and get your symptoms checked. The type of womb cancer caused by tamoxifen is nearly always curable. Tamoxifen can also slightly increase the risk of blood clots in the leg or lung. These risks are usually outweighed by the benefit of tamoxifen in reducing the chance of the cancer coming back. 

 

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What side effects are

Hormone therapy for early breast cancer affects people differently. Some people have more side effects than others. Unfortunately it is something we can’t predict before you start treatment. You may find that you have one side effect but not another. Many women find that the side effects are often worse at the start of treatment. They usually settle down after a few weeks or months.

Side effects may sometimes have positive effects for some women. A Cancer Research UK study in 2008 looked at hormonal therapy side effects in women taking tamoxifen or anastrozole. Women who had effects such as hot flushes, night sweats and painful joints within three months of starting treatment were 10% less likely to have a recurrence of breast cancer, compared to women who did not have side effects.

 

Why side effects happen

Hormones occur naturally in the body and control the growth and activity of cells. We know that the female hormones, oestrogen and progesterone, can help some types of breast cancer to grow. Hormone therapy works by reducing the amount of oestrogen in the body or blocking its effects. Some hormone therapies change the level of progesterone. 

You get side effects with hormone therapies because they lower your levels of some hormones or else they stop your body from being able to use the hormones.

The side effects you have will depend on the type of hormone treatment and the specific drug that you have. You can find detailed information about the side effects of individual hormone therapies by clicking on these links

 

General side effects of hormone therapy

Some side effects are common to most of the hormone therapies used to treat breast cancer. Most people only have one or two of these effects and they may be mild. 

If you are finding the side effects difficult to cope with tell your doctor or specialist nurse. They may be able to suggest ways of coping with them. It can help some women to change hormone therapy if one is causing a lot of side effects or if the effects are severe. 

An American trial studied women who had severe side effects with their aromatase inhibitor drug and wanted to stop taking it. The trial found that changing to a different type of aromatase inhibitor meant that the women could continue with hormone treatment for longer. 

The common side effects of hormone therapy include

Hot flushes and sweats

These can be difficult to cope with. Hot flushes are one of the most common symptoms women have when going through the menopause. You get hot flushes and sweats because you have lower levels of oestrogen. All the hormone therapies used for breast cancer cause hot flushes. They are particularly common with luteinising hormone (LH) blockers because these drugs stop the body making any oestrogen. Just under half of the women who take tamoxifen have hot flushes. Fewer women have hot flushes with aromatase inhibitors.

Hot flushes usually reduce with time for most women. But some women find they continue during treatment. You may find that certain things, such as tea and coffee or spicy food, trigger them and that it helps to cut down on these.

Doctors sometimes prescribe medicines to control hot flushes and sweats. They may try a drug called clonidine or anti depressants such as venlafaxine. Anti depressants can reduce hot flushes by just over half in women who have had breast cancer. But doctors don’t recommend some types of anti depressant, such as paroxetine or fluoxetine, for women taking tamoxifen. These types may interfere with how well tamoxifen works. 

You can find more detailed information about hot flushes and sweats caused by a lowering of the amount of sex hormones in your body.

Changes to your periods

If you have gone through your menopause this won’t affect you. 

If you are premenopausal and taking tamoxifen your periods may become lighter and irregular or they may stop completely. If you are taking a luteinising hormone (LH) blocker your periods will stop completely. They sometimes start again within 6 to 12 months of the end of treatment. But for some women they don’t start again, and they have an early menopause. This is more likely if you are close to the age of your natural menopause.

Less interest in sex

Many factors can lower your interest in sex when you have cancer, including hormone treatments. In women, the adrenal glands make small amounts of the hormone androgen, which affects sex drive. A lower level of androgen reduces your interest in sex. Other factors that can affect sex drive include vaginal dryness, tiredness, mood changes, worry, and loss of confidence.

Once the treatment has finished, your sex drive usually goes back to how it was before treatment. Most women take hormone treatment for at least 2 to 5 years. The impact it has on your sex drive sometimes becomes less over time, as you adjust to the treatment. It can help to take your time and not rush things. Think about why you feel less like sex. For example

  • Are you tired? Could you get more rest?
  • How do you feel about how you look and how other people see you?
  • Has your confidence been knocked. Are there things that you can do to boost your confidence? 

Try to be open and talk to your partner about how you feel. Although it can be difficult, just talking about it may help. As well as your partner, you could try talking to a close friend, or your doctor or nurse. If you are feeling sad and depressed, counselling may help. Your doctor may be able to give you treatment for tiredness or depression, if that’s right for you.

There is information about coping with a low sex drive in our sex, sexuality and cancer section and on our sex and sex hormone symptoms page.

Vaginal dryness or discharge

This is an uncomfortable and sometimes painful side effect of hormone treatment. Dryness can make you more likely to get vaginal infections. It can also put you off having sex. Vaginal discharge is more common with tamoxifen than with the other types of hormone treatment.

A number of different creams and gels are available to help with vaginal dryness. Talk to your doctor or nurse about what you can use. An oestrogen cream might be possible as the amount of oestrogen in the cream is very small. There is information about managing vaginal dryness in the sex and cancer section.

Feeling sick

People often feel sick for the first few days of taking hormone treatment and then it may settle down. If you are taking tablets it might help to take them after you have eaten. If you feel very sick, and can't eat and drink, talk to your doctor or nurse. You may be able to have anti sickness tablets.

Painful joints

Painful joints especially occur with aromatase inhibitors and luteinising hormone (LH) blockers, but any of the hormone treatments may cause them. You can take a mild pain killer such as paracetamol or ibuprofen. If the pain continues, tell your doctor or nurse.

Mood changes

Mood changes are a common side effect of hormone treatment. Coping with them can be difficult for you and also for your family and friends. You may find that you have mood swings, or that you feel very sad. Many women find that these mood changes improve with time but talk to your doctor or nurse if they carry on.

We have information about mood changes and sex hormones.

Tiredness

It is common to feel tired and worn out (fatigued) when having hormone treatment. Coping with this side effect be difficult and frustrating. Your energy levels may improve with time but you may find that you have some tiredness for the whole time you are having the treatment.

We have information about managing fatigue.

 

Possible longer term side effects

There are a few possible longer term side effects of hormone treatments. These are rarer and include

Bone thinning

Any drugs that block your body from making oestrogen can make you more prone to bone thinning or osteoporosis. Bone thinning can increase your chance of breaking a bone. It is a particular problem with taking aromatase inhibitors for a long time. Before you start treatment, or shortly afterwards, you should have a DEXA scan to check the strength of your bones (bone density). Your doctor may recommend that you don’t have aromatase inhibitors if you already have some weakening of the bones (osteoporosis).

If you are taking an aromatase inhibitor drug your doctor may also give you calcium and vitamin D supplements to help lessen the effect on your bones. Exercise can help lower your risk of developing bone problems but it needs to be weight bearing exercise, such as walking, running or gym work. You can find detailed information about osteoporosis risk and hormone therapy on this website.

Research has shown that if you are taking tamoxifen, and have had your menopause, you are less likely to have bone problems than women who haven’t had tamoxifen. Tamoxifen can help to maintain bone strength. So it may help to prevent bone problems while you are having breast cancer treatment.

We have information about bone loss and sex hormones.

Womb cancer

If you are taking tamoxifen, there is a very small risk of developing cancer of the womb. If you have any abnormal bleeding you should see your doctor and get your symptoms checked. The type of womb cancer caused by tamoxifen is nearly always curable. The benefit of taking tamoxifen in reducing the chance of the cancer coming back outweighs the small risk of developing womb cancer.

The other hormone treatments used for breast cancer do not increase your risk of womb cancer.

You can find information about womb cancer on this website.

Eyesight changes

Tamoxifen can cause eyesight changes but this is very rare. If you notice any changes in vision, tell your doctor. You may need to have an eye check up.

Risk of blood clots

Tamoxifen can cause a small increase in the risk of blood clots in the leg or lungs. There is information about cancer and blood clots and their treatment on this website.

 

Information about hormone therapy trials for breast cancer

You can find out about hormone therapy trials for breast cancer on our clinical trials database. If you want to see all the trials, tick the boxes for closed trials and trial results.

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Updated: 2 August 2014