Hormone therapy for metastatic breast cancer
Hormone therapies try to stop oestrogen from helping cancer cells to grow. They are often used as the first treatment for metastatic breast cancer.
How does hormone therapy work?
Some breast cancers are oestrogen receptor (ER) and progesterone receptor (PR) positive. This means they are encouraged to grow by the female hormone oestrogen.
- All hormone therapies try to stop oestrogen from helping ER positive breast cancer and PR-positive breast cancer to grow.
- Hormone therapies only work for breast cancers that are hormone-receptor positive.
- If you had a hormone therapy to treat your primary breast cancer, you may need a different type to treat the metastatic cancer.
- The benefits of hormone therapy can sometimes last for several years.
What's the difference between hormone therapy and hormone replacement therapy (HRT)?
- Hormone therapy drugs reduce oestrogen levels or block oestrogen from helping cancer cells to grow. Hormone therapy is also called ‘anti-hormone therapy’ because it works ‘against’ hormones.
- HRT increases the level of oestrogen in your body when levels are low because of the menopause.
If hormones help your cancer to grow, you will probably be advised not to take HRT. Ask your consultant about this.
Types of hormone therapy drugs
Different types of hormone therapies work in different ways. You might have several types of hormone therapies one after another to keep your disease under control.
Anti-oestrogen drugs
- How do they work?
Anti-oestrogen drugs stop the hormone oestrogen from helping oestrogen-receptor positive cancer cells to grow. They do this by stopping oestrogen from attaching to the receptors on the cancer cells. - What drugs are used?
Examples of anti-oestrogen drugs include tamoxifen and fulvestrant. Tamoxifen can be given before or after the menopause. Fulvestrant is usually given to people who have been through the menopause. - How are they given?
They are usually given in tablet form. Some may be given as a liquid to be taken by mouth or as an injection.
Aromatase inhibitors
- How do they work?
Aromatase inhibitors block the enzyme aromatase, which changes hormones called androgens into oestrogen. - What drugs are used?
Examples of aromatase inhibitors include anastrozole (Arimidex®), letrozole (Femara®) and exemestane (Aromasin®) - How are they given?
They are given as tablets. - What are the side-effects?
Aromatase inhibitors can cause side-effects. They can cause vaginal dryness, nausea, and muscle and joint pain. Tell your medical team if you are bothered by any side-effects. Bone density scans may be done before starting treatment and regularly during treatment, as the drug can increase bone loss. There are treatments that can improve your bone strength.
Ovarian treatments
If you have not been through the menopause and your metastatic breast cancer is oestrogen-receptor positive, your doctor might suggest an ovarian treatment. Ovarian treatments stop your ovaries from making oestrogen.
The treatments can be:
- Temporary (ovarian suppression)
- Permanent (ovarian ablation)
You will usually have these treatments in combination with an aromatase inhibitor or an anti-oestrogen drug.
There are 3 ways to stop your ovaries from making oestrogen:
Drug treatment
Drugs are used to ‘switch off’ your ovaries temporarily. The drugs change the levels of the hormones released in your brain that control how your ovaries work. One example of this type of drug is goserelin (Zoladex®). When you stop taking the drug, your ovaries should start producing oestrogen again and your periods should return. If you are close to menopausal age, your periods may not return.
Surgery
Surgery involves removing your ovaries. Your periods will stop immediately if your ovaries are removed.
Radiotherapy
Radiotherapy uses high-energy X-rays to stop your periods so your ovaries will no longer produce oestrogen.
Surgery and radiotherapy are rarely used to stop the ovaries from making oestrogen. Most people will have drug treatment.
Both surgery and radiotherapy will permanently stop your
ovaries from working, so you will no longer have periods.
How does the menopause affect the choice of hormone therapy?
A natural menopause means you have not had a menstrual period for 12 months, where there is no other external cause for not having periods, such as medication. Whether you have reached menopause or not affects the choice of hormone therapy.
Treatment before the menopause (pre-menopausal)
If you haven’t been through the menopause, all types of hormone therapies are suitable for you. You may be given a combination of treatments, usually:
- An ovarian treatment to stop your ovaries from producing oestrogen
- An anti-oestrogen drug or an aromatase inhibitor to stop oestrogen from helping breast cancer cells to grow
Treatment after the menopause (post-menopausal)
After the menopause the ovaries stop producing oestrogen, so ovarian treatments are not helpful for you. You will most likely be treated with either:
- An aromatase inhibitor
An anti-oestrogen drug
Breast hormone therapy videos
What are the side-effects of hormone therapy?
- Hormone therapy may cause short- or long-term side-effects.
- Usually the side-effects are mild and may reduce over time.
- You should get an information sheet about your hormone therapy, which will tell you about possible side-effects.
- As with all treatments, side-effects can vary. Talk to your doctor if you’re troubled by any side-effects.
Possible side-effects include:
If you are still having periods, hormone therapy may cause periods to become irregular, lighter or stop altogether.
The physical effects of this may include menopausal symptoms like hot flushes, night sweats, anxiety, lowered sex drive, dry skin and dryness of your vagina. Read more about managing menopausal symptoms.
Your periods may come back after treatment, but if you’re close to the age where you would be going through your natural menopause, it’s less likely that your periods will come back.
Oestrogen helps to keep your bones strong and healthy. If your treatment lowers the amount of oestrogen in your body, there is a risk that your bones may become weaker and more likely to break.
You may have regular scans to monitor your bone health during your treatment. You should also stop smoking, take regular exercise and eat calcium-rich foods. Ask your doctor about taking calcium
supplements and about the best exercise for you. Some activities may not be recommended if your bones are weak
Drugs may be prescribed if there is serious bone loss (osteopenia or osteoporosis).
Read more about bone pain and weakened bones
Some hormone therapies can cause your periods to stop permanently, which means you will not be able to get pregnant naturally. It is not easy to come to terms with infertility. It can be more distressing if you are already coping with metastatic breast cancer. We have more information about infertility.
Some drugs can cause the lining of your womb to become thickened, which may cause changes to the timing of your period or the amount of period bleeds. Some drugs can put you at a small risk of developing cancer of the womb. You should report any vaginal bleeding to your doctor.
Some drugs slightly increase the risk of blood clotting. Tell your doctor if you have any chest pain, swelling, tenderness in your legs or arms or any new shortness of breath.
Some drugs may cause pains and aches in your muscles or bone joints.
Managing side-effects
Ask your doctor or nurse what side-effects you can expect and how to manage them. If you continue to find them a problem, talk to your doctor or nurse. For more information about side-effects, call our Support Line on 1800 200 700 or visit a Daffodil Centre.
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