1. What is hormone therapy?
2. Who it’s for
3. When hormone therapy is given
4. Hormone therapy drugs
5. Hormone therapy for reducing the risk of breast cancer
6. Side effects of hormone therapy
7. Stopping hormone therapy

1. What is hormone therapy?

Some breast cancers use the hormone oestrogen in the body to help them grow. 

Hormone therapy is a treatment that stops the effect of oestrogen on breast cancer cells. 

Different hormone therapy drugs do this in different ways.

Hormone therapy is also sometimes called endocrine therapy. 

2. Who it’s for

Hormone therapy will be prescribed if your breast cancer is oestrogen receptor (ER) positive. ER positive means oestrogen is helping the cancer grow.

All breast cancers are tested to see if they are ER positive using tissue from a biopsy or after surgery. 

If your cancer is ER positive, your specialist will discuss with you which hormone therapy they think is most suitable.

3. When hormone therapy is given

After surgery

Hormone therapy is usually started after surgery.

It’s given to reduce the risk of breast cancer coming back. It may also reduce the risk of a new breast cancer developing.

If you’re having radiotherapy after surgery but not chemotherapy, hormone therapy may be started during or after the radiotherapy.

If you’re having chemotherapy after surgery, hormone therapy will usually start after chemotherapy has finished.

If you’re having trastuzumab (Herceptin), hormone therapy may be given at the same time.

Hormone therapy may be recommended after breast-conserving surgery for DCIS. Your specialist will discuss whether it’s appropriate for you.

Before surgery

Sometimes, hormone therapy may be given before surgery to reduce the size of the cancer, or if surgery is delayed for some reason.

Occasionally, hormone therapy is given when surgery is not an option, for example if someone has a lung or heart condition.

If cancer has come back or spread

Hormone therapy can be used to treat breast cancer that has come back (recurrence) or that has spread to another part of the body (secondary breast cancer). 

It’s given either alone or with other treatments, depending on what treatments you had before.

If your breast cancer came back during or after treatment with hormone therapy, you may be offered a different type of hormone therapy.

4. Hormone therapy drugs

The most common hormone therapy drugs used to treat breast cancer are:

If you’re prescribed tamoxifen or an aromatase inhibitor after surgery, you will usually take these for five years. However, some people will be recommended to continue taking them for up to 10 years.

How long other hormone drugs are given for varies from person to person.

If you’re taking hormone therapy because your breast cancer has come back or spread, you’ll usually continue taking it for as long as it is effective.

5. Hormone therapy for reducing the risk of breast cancer

Women at moderate or high risk of breast cancer because of their family history may be offered hormone therapy to reduce their risk of developing breast cancer.

Drugs used to reduce the risk of breast cancer in women who have not had breast cancer include:

These drugs are usually taken for five years.

6. Side effects of hormone therapy

Like any treatment, hormone therapy can cause side effects. Everyone reacts differently to drugs and some people have more side effects than others. 

Side effects can often be managed and those described here will not affect everyone.

Some side effects are common to all hormone therapies, while others are specific to certain drugs. You can read about specific side effects on our individual drug pages (listed above).

If you’re concerned about any side effects, whether or not they are listed here, talk to your treatment team as soon as possible.

Common side effects

The most common side effects of hormone therapy are menopausal symptoms such as:

  • Hot flushes
  • Night sweats
  • Vaginal dryness
  • Reduced sex drive
  • Mood changes

These symptoms are often more intense than when the menopause happens naturally.

Other common side effects with most hormone drugs include:

  • Joint or muscle pain and stiffness
  • Headaches
  • Feeling sick
  • Effects on the bones
  • Tiredness or extreme tiredness (fatigue)

Managing side effects

Many people find the side effects of hormone therapy drugs difficult to cope with.

If side effects are putting you off taking your hormone therapy, talk with your cancer specialist before making any decisions to stop it. They may suggest a short break from treatment to see if side effects improve. 

There may be ways to improve your symptoms or your cancer specialist may suggest you change to a different drug.

If you have ongoing side effects from hormone therapy, talk to your cancer specialist so they can discuss with you the best way to manage them.

You may also find the information following useful:

Talk to other people taking hormone therapy on our online Forum.

7. Stopping hormone therapy

Your treatment team will tell you when to stop taking hormone therapy. You will not need to stop taking it gradually.

Some women worry about stopping hormone therapy, but it will continue to reduce the risk of breast cancer coming back for many years after you finish your treatment. This is known as the carryover effect and may last for five years or longer. 

If you have any worries or questions about taking or stopping hormone therapy, you can call our Helpline for further information and support.

Last reviewed: March 2021
Next planned review begins 2023

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