Hormone therapy for breast cancer

Pharmacist holding box of pills

Treating oestrogen-receptor positive cancer 

Some breast cancers have extra receptors on their cells’ surface that attach to the female hormone oestrogen. This is called oestrogen- or hormone-receptor-positive cancer. The hormones help the cancer cells to grow faster.

Oestrogen-receptor-positive breast cancer is common:

  • Just over half of women who get breast cancer before the menopause have oestrogen-receptor-positive cancer.
  • About 3 in 4 women who get breast cancer after the menopause have oestrogen-receptor-positive cancer.

A small number of breast cancers are sensitive to the hormone progesterone only. In this case, your doctor will talk to you about the possible benefits and risks of hormone treatment.

Ovarian suppression. Ovarian suppression means reducing the amount of oestrogen made by the ovaries or stopping the ovaries from making oestrogen. Hormone therapy drugs are the main way to do this. 

When will I have hormone therapy?

You might have hormone therapy:

Before surgery to try to make the tumour smaller and easier to remove.

After breast surgery to help prevent cancer spreading or coming back. 

As your main treatment, where surgery is not possible.

How is hormone therapy given? 

Hormone therapy is often given as tablets, or you may have an injection under your skin. It depends on the type of drug.

Other ways to reduce oestrogen levels in your body

Most women will have hormone therapy drugs, but surgery and radiotherapy can also reduce oestrogen levels:

  • Surgery. This is where your ovaries - the main source of oestrogen for pre-menopausal women - are removed. Small amounts of oestrogen will still be produced by other cells in the body. 
  • Chemotherapy. Chemotherapy may stop your ovaries from working normally. This can also reduce oestrogen levels. The effect on your ovaries may be reversible, depending on your age.

Side-effects of hormone therapy

Hormone therapy may cause short- or long-term side-effects:

Menopausal symptoms after hormone therapy

Hormone therapy can put you into an early or temporary menopause or cause menopausal-like symptoms, like hot flushes.  A menopause caused by breast cancer treatment can be quite sudden.

Read more about managing menopausal symptoms. 


If you haven't yet gone through the menopause, you may be at risk of osteoporosis (brittle bones). Talk to your doctor or nurse about how it can be prevented.

Blood clotting

Some treatments slightly increase the risk of blood clotting. Tell your doctor if you have any pain, swelling, or tenderness in your legs or arms.

Thickened womb

Some drugs can cause the lining of your womb (uterus) to become thickened or put you at small risk of developing cancer of the womb. Tell your doctor if you have any vaginal bleeding between periods or after sex while you are having treatment.

Bone loss and pain

Some hormone therapy drugs may increase bone loss and cause pains and aches in your muscle or bone joints. If your treatment has this effect, you may have bone density (DEXA) scans before starting treatment and regularly while on hormone therapy. You should also stop smoking, take regular exercise and eat foods with calcium. Ask your doctor about calcium supplements. Drugs may be prescribed if there is serious bone loss (osteopenia).

Read more about bone strengthening drugs and ways to improve bone health. 

Fertility side-effects

If you have drug treatment to switch off oestrogen production you won’t be able to get pregnant while you are being treated and for a time afterwards. Once therapy is stopped, the ovaries should start working again within five to six months for most women.

If you have surgery to remove your ovaries, you will not be able to have children afterwards. Read more about fertility. 

Pregnancy and hormone therapy

Hormone therapy drugs can affect a developing baby, so it’s important to avoid pregnancy during and for a time after treatment. Ask your doctor about this.

Coping with hormone therapy side-effects

Coping with a diagnosis of breast cancer is never easy, and the added stress of an early menopause brought on by treatment can make this particularly difficult.

You may find that going through the menopause prematurely can create feelings of loss, and you may even feel isolated from women your own age.

Some women may find it difficult to come to terms with the fact that they will not be able to start a family or have more children. Whatever your feelings, remember that you do not have to cope on your own. Your cancer specialist and breast care nurse are there to provide information and support to you and your family.

You might find it easier to share your feelings with someone who has had a similar experience to you.

Our Survivor Support programme can put you in touch with a trained volunteer who has been through a breast cancer diagnosis. Our trained volunteers are available to provide emotional and practical support to anyone going through or finished with their treatment.

For more information

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1800 200 700

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Is hormone therapy suitable for me?

If you have hormone-receptor positive cancer, hormone therapy will probably be helpful for you.  

If your breast cancer is not sensitive to hormones, hormone therapy will not be of benefit. You may be offered chemotherapy, or no further treatment may be needed.

Hormone therapy drugs work in different ways...

By blocking the receptors on the cancer cells

This means oestrogen cannot attach to the cells. An example of a hormone therapy drug that works in this way is tamoxifen.

By blocking the production of oestrogen in your body fat

Drugs called aromatase inhibitors stop the enzyme aromatase from changing the hormone androgen into oestrogen. These drugs are for women after the menopause (postmenopausal), who don’t produce oestrogen in their ovaries any more. Examples of aromatase inhibitors include anastrozole (Arimidex®), letrozole (Femara®) and exemestane (Aromasin®).

By stopping your ovaries from making oestrogen in prememopausal women 

Hormone therapy drugs that work in this way are called luteinising hormone-releasing hormone (LHrH) analogues. They change the levels of hormones released in your brain that control how your ovaries work. The effects of these drugs are usually reversible once the drug is stopped. It usually depends on your age. An example of an LHrH analogue is goselerin (Zoladex®).