Hormonal therapies for breast cancer

The hormones oestrogen and progesterone can encourage some breast cancers to grow. For women with oestrogen-receptor positive cancers, hormonal therapy can reduce the amount of oestrogen in the body. This can delay the growth of the cancer. Some women also have hormonal therapy to reduce the chances of breast cancer coming back.

The type of therapy you have depends on whether you have been through the menopause, the risk of the cancer returning and the likely side effects of the therapy.

Aromatase inhibitors (AIs) are the main hormonal therapy given to women who have been through the menopause. AIs can cause bone thinning. You will have scans to check your bone health.

Tamoxifen is the main hormonal therapy for women who haven’t been through the menopause. This treatment may bring on a temporary or permanent menopause with side effects such as flushes and weight gain.

Oestrogen levels can also be reduced by having an operation to remove the ovaries or having radiotherapy to the ovaries. Both these procedures cause permanent infertility.

What is hormonal therapy

Hormones help to control how cells grow and what they do in the body. The hormones oestrogen and progesterone can encourage some breast cancer cells to grow (particularly oestrogen).

Hormonal therapies reduce the level of oestrogen in the body or prevent it from attaching to the cancer cells. They only work for women with oestrogen-receptor positive cancers.

You may have hormonal therapy to reduce the risk of breast cancer coming back and to protect your other breast. You’ll usually take hormonal therapy for a number of years.

Your cancer specialist will start your hormonal therapy after surgery or after chemotherapy, if you have it. Sometimes doctors prescribe hormonal therapy before surgery to shrink a large cancer, which may mean you avoid having a mastectomy.

The type of hormonal therapy you have depends on:

  • whether you’ve been through the menopause or not
  • the risk of the cancer coming back
  • how the side effects are likely to affect you.

We have information about individual hormonal therapy drugs.


Taking your hormonal therapy

Hormonal therapy reduces the risk of breast cancer coming back. It’s very important to take it for as long as your cancer specialist prescribes it. It may help to build taking it into your daily routine so it becomes a habit.

Most women cope well with the side effects of hormonal therapy. They may be more troublesome in the first few months, but they usually get better over time. If you continue to have problems or if your side effects are difficult to cope with, talk to your breast care nurse or doctor. They can prescribe drugs to help and advise you on other ways of coping. If the side effects don’t improve and are very troublesome, your cancer specialist may suggest switching to a different type of hormonal therapy.


Hormonal therapy after menopause

After the menopause, the ovaries no longer produce oestrogen. But women still make some oestrogen in their fatty tissue. If you have been through your menopause, your doctor may prescribe one of the following:

  • an aromatase inhibitor such as anastrozole (Arimidex®), letrozole (Femara®) or exemestane (Aromasin®)
  • the anti-oestrogen drug tamoxifen and an aromatase inhibitor (one type is given after the other)
  • tamoxifen alone.

Aromatase inhibitors (AIs)

Aromatase inhibitors (AIs) are the main hormonal therapy used in post-menopausal women. They stop oestrogen being made in the fatty tissue after the menopause. Your doctor may prescribe an aromatase inhibitor, such as anastrozole, letrozole or exemestane.

These drugs are taken daily as a tablet. Side effects can include:

  • tiredness
  • joint and muscle pain
  • hot flushes.

If taken over a long period of time, AIs can cause bone thinning (osteoporosis). You will have a scan called a DEXA (dual-energy x-ray absorptiometry) scan, to check your bone health (density) before starting an AI.

If you are at risk of osteoporosis, your cancer doctor may prescribe drugs called bisphosphonates to protect your bones. They will probably also advise you to take calcium and vitamin D supplements to help with your bone strength.

Tamoxifen

Tamoxifen is a drug that stops oestrogen from attaching to breast cancer cells and encouraging them to grow. It is occasionally used in post-menopausal women.

Some women take it for a few years and then go on to take an aromatase inhibitor.

Doctors sometimes prescribe tamoxifen if you have problems with your bones or troublesome side effects with AIs. Tamoxifen doesn’t cause bone thinning in post-menopausal women, but it can slightly increase the risk of womb cancer. It’s important to tell your doctor if you have any vaginal bleeding.


Hormonal therapy before the menopause

Before the menopause, the ovaries produce oestrogen. If you haven’t been through menopause (pre-menopausal), your doctor may prescribe one of the following:

  • the anti-oestrogen drug tamoxifen
  • a drug, such as goserelin (Zoladex®), that stops the ovaries producing oestrogen (ovarian suppression)
  • surgery to remove the ovaries (ovarian ablation)
  • a combination of tamoxifen with either Zoladex or ovarian ablation (this may be an option for women who don’t want to have chemotherapy).

Some hormonal therapies bring on a temporary or permanent menopause. If you have an early menopause, you will have a scan called a DEXA (dual-energy x-ray absorptiometry) scan to check your bone health.

Women at risk of bone thinning (osteoporosis) may be prescribed drugs called bisphosphonates to protect their bones and are advised to take calcium and vitamin D supplements.

Tamoxifen

Tamoxifen is the main hormonal therapy for women who have not been through the menopause. It’s taken daily as a tablet. The side effects are similar to the effects of the menopause and may include:

  • hot flushes and sweats
  • weight gain
  • tiredness.

Tamoxifen can slightly increase your risk of a blood clot.

You’ll usually have tamoxifen for at least five years. But recent trial results show that taking it for 10 years can reduce the risk of the cancer coming back further. You can talk to your doctor about this. It won’t be suitable for everyone, especially if you have side effects or want to have children. If you’re close to your menopause when you start tamoxifen, your doctor may change your treatment to an aromatase inhibitor after a few years.

Drugs that stop the ovaries producing oestrogen

Zoladex stops the production of oestrogen in the body. It does this by stopping the pituitary gland in the brain from sending messages to the ovaries to produce oestrogen. This stops the ovaries producing oestrogen and causes a temporary menopause. The side effects are similar to menopausal symptoms and include:

  • hot flushes and sweats
  • joint pain
  • low sex drive.

Your nurse will give you Zoladex as a monthly injection under the skin of the tummy (abdomen). When you finish treatment, your ovaries usually start to produce oestrogen again. This means your periods will come back. If you were close to your menopause when you started Zoladex, this may not happen.

Permanently stopping the ovaries working (ovarian ablation)

Other ways of lowering oestrogen levels include stopping the ovaries from working. Doctors sometimes call this ovarian ablation. It can be done with a small operation to remove the ovaries or, rarely, with a short course of radiotherapy to the ovaries. Your doctor may ask you to choose between taking Zoladex or having ovarian ablation.

The operation can be done during a short stay in hospital using keyhole surgery. The surgeon makes a small cut in the tummy area and inserts a thin tube with a tiny light and camera on the end (laparoscope). The surgeon removes the ovaries through the cut using the laparoscope, which has small surgical instruments attached. Women usually recover quickly from this type of operation.

If you have surgery, your periods will stop straight away. After radiotherapy, women usually have one more period before their periods stop completely. It’s important to use contraception for three months after radiotherapy.

Both methods (surgery and radiotherapy) cause a permanent menopause. Becoming infertile because of cancer treatment can be very hard to cope with. There’s more information on the support that’s available in our section on the emotional effects of cancer.

We also have more information about ovarian ablation and coping with menopausal effects.