Trastuzumab is a cancer drug. It is usually used to treat a type of breast cancer called HER2 breast cancer. It can also be used to treat certain cancers of the stomach or the gullet (oesophagus) that have spread.
Trastuzumab only works when the cancer cells have high levels of a protein called human epidermal growth factor receptor 2 (HER2). You will have tests first to find out whether trastuzumab is a suitable treatment for you. It may also be used to treat other types of cancer as part of a research trial.
It’s best to read this information with our general information about the type of cancer you have.
What is trastuzumab and how does it work?
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Trastuzumab is one of a group of cancer drugs called monoclonal antibodies. Monoclonal antibodies are sometimes called targeted therapies because they work by ‘targeting’ specific proteins (receptors) on the surface of cells.
Some cancers have too much of a protein called human epidermal growth factor receptor 2 (HER2) on the surface of their cells. These are called HER2-positive cancers. The extra HER2 receptors stimulate the cancer cells to divide and grow. Trastuzumab locks on to the HER2 protein and blocks the receptor. This stops the cells from dividing and growing.
There are different tests to measure HER2 levels in cancer cells. These tests are done on tissue taken during a biopsy or surgery to remove the cancer.
We have more information about HER2 and breast cancer, including HER2 testing.
When is Trastuzumab used?
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Trastuzumab is a standard treatment for people with HER2-positive breast cancer. It is given after, or at the same time as, chemotherapy, to reduce the risk of the cancer coming back. You can also have trastuzumab to treat breast cancer that has come back or spread to other parts of the body (secondary breast cancer). In this situation, it’s either given on its own or in combination with chemotherapy and/or hormonal therapy.
Stomach and oesophageal cancer
Trastuzumab may be used to treat certain people with advanced HER2-positive stomach cancer or cancer of the oesophagus where it joins with the stomach. In this situation, trastuzumab is given in combination with chemotherapy.
The National Institute for Health and Care Excellence (NICE) advises the NHS in England and Wales on new treatments. NICE recommends trastuzumab for people with advanced stomach or oesophageal cancer. The Scottish Medicines Consortium (SMC), a similar organisation to NICE in Scotland, has not approved its use for these cancers. NICE’s guidance is supported in Northern Ireland.
We have more information on what you can do if a treatment isn’t available.
How is trastuzumab given?
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You can have trastuzumab as a drip into a vein (intravenous infusion) or as an injection under the skin (subcutaneous). You can usually have it in the chemotherapy day unit or a clinic.
You usually have trastuzumab every three weeks or once a week. If you have early-stage breast cancer, you’ll have trastuzumab for a year. If the cancer is advanced or has spread, you usually have trastuzumab for as long as it is controlling the cancer.
As a drip
The nurses give you the first dose (infusion) slowly, usually over an hour and a half. You will stay in hospital for a few hours afterwards so they can monitor you for any reaction. If you don’t have any problems with the first treatment, you can have the following infusions over about 30–90 minutes and go home an hour later.
As an injection under the skin
A nurse gives you the injection into your thigh. This only takes a few minutes. They swap the injection site between your left and right thigh. After the first injection you’ll be monitored for a few hours to make sure you don’t have a reaction. But after the next injections you’ll be monitored for a much shorter time.
Possible side effects of trastuzumab
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We explain the most common side effects of trastuzumab below. But we don’t include all the less common ones that are unlikely to affect you. You may get some of the side effects we mention, but you are very unlikely to get all of them. If you are taking other drugs as well, you may have some side effects that we don’t list here.
Always tell your doctor, nurse or pharmacist about the side effects you have. They can prescribe drugs to help control them and give you advice about managing them.
Side effects during treatment
The following side effects may happen during treatment with trastuzumab, or a few hours after it. They are more likely to happen with the first dose and much less likely to happen with the next doses.
The nurses will closely monitor you for signs of this during and after your treatment. Signs may include a skin rash, itching, wheezing, difficulty breathing and breathlessness. Let your nurse know straight away if you have any of these symptoms. They may give you drugs called antihistamines before your treatment to reduce the chance of an allergic reaction. If you have a reaction, the nurses will treat it quickly.
If you develop any of the signs or feel unwell after you get home, contact the hospital straight away for advice.
These may include a headache, a high temperature (fever) and chills, feeling sick (nausea) or being sick (vomiting). These symptoms can be controlled or reduced with medicines, which your doctor can prescribe for you. They generally get better within a few hours after the trastuzumab is given.
Common side effects after treatment
If you get headaches, let your doctor or nurse know. They can give you painkillers to relieve this.
This is usually mild, but your doctor can prescribe anti-sickness (anti¬-emetic) drugs to reduce sickness or vomiting. Tell your doctor if it doesn’t get better.
Loss of appetite and taste changes
Try to eat small meals regularly. If your appetite doesn’t improve, let your nurse or dietitian know. They can give you advice on getting more calories and protein in your diet. Sucking boiled sweets can sometimes help get rid of a bitter or metallic taste. Your nurse can give you more advice.
Abdominal (tummy) pain or indigestion
Let your doctor or nurse know if you have tummy pain or indigestion. They can prescribe drugs to help reduce these side effects.
Diarrhoea or constipation
This can usually be easily controlled with medicine, but tell your doctor if it’s severe or continues. It's important to drink plenty of fluids if you have diarrhoea.
Drinking at least two litres (three and a half pints) of fluids every day will help with constipation. Try to eat more foods that contain fibre (such as fruit, vegetables and wholemeal bread) and do some regular, gentle exercise.
Tiredness and feeling weak
Feeling tired is a common side effect. Try to pace yourself and get as much rest as you need. It helps to balance this with some gentle exercise, such as short walks. If you feel sleepy, don’t drive or operate machinery.
Joint and muscle pain
You may have pain and stiffness in your joints, and sometimes in your muscles. Tell your doctor or nurse if this happens. They can prescribe painkillers and give you advice.
Watery, sore eyes
Your eyes may become watery. Sometimes they may become sore and inflamed (conjunctivitis). Your doctor can prescribe eye drops if you need them.
Blocked or runny nose, or nose bleeds
Let your doctor or nurse know if you have any of these side effects.
Numb or tingling hands or feet
If you have this, you may also find it hard to fasten buttons or do other fiddly tasks. The symptoms usually improve slowly after treatment finishes. Talk to your doctor if you are worried about this.
Skin or nail changes
Let your doctor know if you get a skin rash. If your nails become brittle and break easily, wear gloves when washing dishes or using detergents to help protect them.
Feeling anxious or dizzy, or difficulty sleeping
If you notice any of these effects, talk to your nurse or doctor.
If you are having trastuzumab as an injection under the skin, you may have discomfort, mild stinging, bruising or redness in the injection area. This is usually mild and temporary.
Effects on the heart
Trastuzumab may affect the way your heart works. Your doctor will ask whether you have any history of heart problems and you’ll have tests to check your heart and blood pressure before starting treatment. You’ll continue to have blood pressure and heart checks during treatment and possibly for a few years after stopping treatment.
Tell a doctor straight away if during or after your treatment you:
have pain or tightness in your chest
have a cough
notice changes to your heartbeat
notice swelling in your arms or legs (caused by a build-up of fluid).
These symptoms can be caused by other conditions, but it’s important to get them checked by a doctor. If you develop heart problems, it can be treated with tablets. We have more detailed information about heart health and cancer treatment.
Trastuzumab can reduce your number of white blood cells, which fight infection. This is more likely if you are having chemotherapy at the same time. You may be more likely to get an infection.
Contact the hospital straight away if:
your temperature goes over 37.5°C (99.5°F) or over 38°C (100.4°F), depending on the advice given by your healthcare team
you suddenly feel unwell, even with a normal temperature
you have symptoms of an infection – this can include feeling shaky, a sore throat, a cough, diarrhoea or needing to pass urine a lot.
Effects on the lungs
Always tell your doctor if you develop wheezing, a cough or a fever, or if you feel breathless. You should also let them know if any existing breathing problems get worse. If necessary, they can arrange for you to have tests to check your lungs.
Other information about trastuzumab
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Some medicines, including ones you can buy in a shop or chemist, may be harmful to take while you’re having trastuzumab. Tell your doctor about any medicines you are taking, including over-the-counter drugs, complementary therapies and herbal drugs.
Your doctor will advise you not to become pregnant or father a child during treatment. This is because the drugs may harm a developing baby. It’s important to use effective contraception during and for seven months after treatment. You can talk to your doctor or nurse about this.
There is a possible risk that trastuzumab may be present in breast milk, so women are advised not to breastfeed during treatment and for a few months afterwards.
It's not known what effects trastuzumab may have on your fertility (your ability to get pregnant or father a child). If you are worried about this, you can talk to your doctor or nurse before treatment starts.
Medical and dental treatment
If you need to go into hospital for any reason other than cancer, always tell the doctors and nurses that you are having trastuzumab. Give them contact details for your cancer doctor.
Talk to your cancer doctor or nurse if you think you need dental treatment. Always tell your dentist you are having trastuzumab.
This information has been compiled using a number of reliable sources, including:
electronic Medicines Compendium (eMC). Summary of product characteristics. www.medicines.org.uk (accessed October 2014).
National Institute for Health and Care Excellence (NICE). Early and locally advanced breast cancer: diagnosis and treatment (CG80). February 2009.
National Institute for Health and Care Excellence (NICE). Guidance on the use of trastuzumab for the treatment of advanced breast cancer (CG81). March 2002.
National Institute for Health and Care Excellence (NICE).Trastuzumab for the treatment of HER2¬positive metastatic gastric cancer (TA208). November 2010.
Scottish Intercollegiate Guidelines Network (SIGN) guidelines. Treatment of primary breast cancer. September 2013.
If you’d like further information on the sources we use, please feel free to contact us.
With thanks to Professor Jaymi Teli, Senior Oncology Pharmacist, who reviewed this information.
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