Hormone therapy for secondary breast cancer

You may have hormone therapy to treat secondary breast cancer. It’s also known as endocrine therapy. It can be taken on its own or you may have it with other drug treatment.

What are hormones?

Hormones are made naturally in the body. They control the growth and activity of normal cells.

Before the menopause Open a glossary item, the ovaries produce the hormones oestrogen and progesterone. After the menopause oestrogen is made in body fat and muscle.

These hormones can stimulate the growth of some breast cancer cells.

Diagram showing Oestrogen

How does hormone therapy work?

Hormone treatments lower the levels of oestrogen or progesterone in the body, or block their effects.

Hormone therapy is only likely to work if the breast cancer cells have oestrogen receptors (ER). Your doctor checks your cancer cells for these receptors when you are diagnosed. 

Around 7 out of 10 breast cancers (70%) have oestrogen receptors. They are called oestrogen receptor positive cancer Open a glossary item or ER positive cancer.

The aim of secondary breast cancer treatment is to control the cancer and give you a good quality of life.

You might have hormone therapy when secondary breast cancer is first diagnosed. Or after you have had treatment with chemotherapy.

Types of hormone therapy

Doctors use different types of hormone therapy for secondary breast cancer.


Tamoxifen is one of the most commonly used hormone therapies for secondary breast cancer. Women who are still having periods (pre menopausal) and women who have had their menopause (post menopausal) can take tamoxifen.

Tamoxifen works by blocking the oestrogen receptors. It stops oestrogen from telling the cancer cells to grow. Tamoxifen belongs to a group of drugs called selective oestrogen receptor modulators or SERMs.

Your doctor may offer you tamoxifen, with treatment to stop your ovaries from working, if you have advanced ER positive breast cancer and are still having periods.

If you are a man with secondary ER positive breast cancer, then your doctor will offer tamoxifen unless you have had tamoxifen treatment before.

You usually have tamoxifen as a tablet. It is also available as a liquid.

Aromatase inhibitors (AIs)

If you have secondary ER positive breast cancer, your doctor will probably offer you an aromatase inhibitor if:

  • you have had your menopause and you have not had any hormone treatment before
  • you have already had tamoxifen treatment

Aromatase inhibitors work by stopping oestrogen being made in body fat after the menopause.

There are several different aromatase inhibitors used to treat secondary breast cancer. They include: 

  • anastrozole (Arimidex)
  • letrozole (Femara)
  • exemestane (Aromasin)

You take them as tablets once a day.

Progesterone (Megace or Provera)

Your doctor may suggest progesterone treatment if your breast cancer stops responding to aromatase inhibitors or tamoxifen.

Progesterone is another hormone that occurs naturally in women. Artificial progesterone can control the growth of breast cancer cells. You can have it as tablets or by injection. The most common types of progesterone are:

  • medroxyprogesterone acetate (Provera)
  • megestrol acetate (Megace)

Fulvestrant (Faslodex)

Fulvestrant (Faslodex) is a type of hormone therapy called an oestrogen receptor antagonist. You can have this if you are post menopausal with secondary breast cancer that is ER positive. You have it if tamoxifen or aromatase inhibitors are no longer controlling your cancer. 

Fulvestrant works in two ways. Firstly, it blocks oestrogen receptors, in a similar way to tamoxifen. But it can also change the shape of oestrogen receptors in the cancer cells, so the oestrogen can’t attach to them. This is called down regulation.

You have fulvestrant as an injection into a muscle every 2 weeks for 3 doses and then once a month. You may have some soreness and swelling around the injection site for a day or 2 afterwards.  

Stopping the ovaries working

Your specialist might suggest treatment called ovarian ablation if you are still having periods. This stops your ovaries from producing oestrogen. 

Breast cancer that are oestrogen receptor positive (ER+) need oestrogen to grow. Most of your oestrogen is made by the ovaries. You have a high level of this until your periods stop (the menopause). Treatment to stop the ovaries from working lowers the levels of oestrogen. This means there is less oestrogen for the cancer to use to grow. 

Your body also makes a small amount of oestrogen from body fat. Treatment to your ovaries will not stop your body from producing these small amounts.

To stop your ovaries from working you may have hormone treatment or surgery. 

Hormone treatment

Doctors might use a type of hormone treatment to stop the ovaries from producing oestrogen. This type of drug is called a luteinising hormone releasing hormone (LHRH). For example, goserelin (Zoladex) and leuprorelin (Prostap, Lutrate). You might have this on its own or with other hormone therapy drugs. You have these drugs as an injection under the skin. 

LHRH drugs work by blocking a hormone made in the pituitary gland Open a glossary item that stimulates your ovaries to make and release oestrogen. This stops your ovaries from working. So you won't have periods or release eggs while you are having the injections.

When you stop taking the drug, your ovaries should start working again. But, if you're close to the age at which your menopause would naturally start, your periods might not start again.


Surgery to remove the ovaries means that you won't produce any more oestrogen. Your doctor and nurse can give you more information about this. 

Removing your ovaries causes you to have a sudden menopause. The symptoms include hot flushes, sweating and mood swings. 

Side effects of hormone therapy

Some side effects are common to all hormone therapies. Some effects vary from drug to drug.

The main side effects of hormone therapy include:

  • hot flushes and sweating
  • changes to your periods if you are pre menopausal
  • less interest in sex
  • vaginal dryness or discharge
  • feeling sick
  • painful joints
  • mood changes
  • tiredness

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.

Tell your doctor or nurse if you have any side effects. They may be able to help reduce them.

Bone thinning (osteoporosis)

A side effect of aromatase inhibitors and goserelin is bone thinning (osteoporosis Open a glossary item) or weakening. This can sometimes cause breaks (fractures) in the bones. If you are starting treatment with an aromatase inhibitor you might have a DEXA scan Open a glossary item first. This is to check your bone strength (bone density).

You might also have calcium and vitamin D supplements to help reduce the effect on your bones.

Early menopause

All the treatments that stop your ovaries working give you an early menopause (even though this may be temporary with hormone injections). Some women find this very difficult to deal with. You are likely to have menopausal symptoms that start very suddenly.

Support for you

It's normal to have lots of questions about hormone treatment for secondary breast cancer.

Talk to your specialist team and breast care nurse. They are there to help and give you more information if you'd like it.

You can call the Cancer Research UK nurses on freephone 0808 800 4040. The lines are open from 9am to 5pm, Monday to Friday. You could talk to them about your hormone treatment options.

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