2. What is a blood clot?
3. The risk of blood clots in people with breast cancer
4. Breast cancer treatments that increase the risk of blood clots
5. Other factors that can increase the risk of blood clots
6. Preventing and treating blood clots
7. If you are in hospital
8. Finding support
People with breast cancer have a higher risk of blood clots. Their risk is higher because of the cancer itself and some treatments for breast cancer.
If the cancer has spread to other parts of the body (secondary breast cancer), this can also increase the risk of clots.
Blood clots can be harmful but are treatable so it’s important to report symptoms as soon as possible. If you develop a blood clot during treatment, your treatment may be put on hold until the clot has been treated.
If you experience any of the following symptoms contact your local A&E department, GP or treatment team straight away:
- pain, tightness, redness/discolouration, heat and swelling typically of the calf, leg or thigh or over a vein
- swelling, redness or tenderness where a central line is inserted to give chemotherapy, for example in the arm, chest area or up into the neck
- shortness of breath, this may be sudden or increases over time
- pain in your chest when you take a deep breath or cough
- tightness in the chest
- unexplained cough (may cough up blood)
Blood clots happen quite often. If you have an injury your blood will clot to reduce bleeding. But your blood may also clot for other reasons.
Clots can form inside veins or arteries. If a blood clot develops in a vein it’s often referred to as a venous thromboembolism (VTE) or venous thrombosis. It can happen in any deep vein but most commonly happens in the legs, thighs or pelvis – you might hear this called deep vein thrombosis (DVT).
A blood clot can break loose from where it was formed and travel from one location in the body to another. A clot becomes harmful when it blocks a blood vessel and stops the blood flow to a part of the body, for example the lung, known as a pulmonary embolism (PE).
The risk of developing a blood clot can be reduced by the use of drugs and other measures.
People with breast cancer may have a higher number of substances called platelets and clotting factors. These play a role in helping the blood to clot and stop any bleeding. Having higher than normal amounts of platelets and clotting factors in the body means the blood is more likely to clot.
Some people with cancer may have lower levels of proteins in the blood that help to keep it thinned. This means a blood clot may be more likely to form, particularly if the cancer affects the liver.
Some treatments for breast cancer may increase someone’s risk of developing a blood clot. These include:
- surgery – after surgery the risk of developing blood clots is highest between 2–10 days after your surgery. Your risk remains higher than normal for up to 90 days following surgery
- chemotherapy – as cells are destroyed by chemotherapy they can release substances that cause blood clots
- targeted therapies such as palbociclib and bevacizumab
- the hormone therapy tamoxifen and to a lesser degree aromatase inhibitors (letrozole, anastrozole and exemesthane)
Both surgery and chemotherapy can damage the walls of blood vessels, which can increase the risk of a blood clot developing. If you’re due to have surgery or chemotherapy let your treatment team know if you have a previous history of blood clots.
Having a central line
A central line is a long intravenous line that’s inserted into a large vein and can be used to give chemotherapy or other drugs.
If you have a central line, such as a Hickman, Groshong or PICC line, it’s possible for a blood clot to form in a vein at the end of the line. Drugs may be given to help prevent this. If this does happen the line may need to be removed to treat the blood clot.
Being less active due to treatment
For some people, their breast cancer treatment makes them feel very tired and weak. This means they’re not as physically active. If you have surgery it may be difficult to get out of bed or to move around normally at first. See If you are in hospital for more information. Inactivity increases the risk of a blood clot as the normal action of the leg muscles helps squeeze the veins to return the blood back towards the heart.
Inactivity on long journeys, such as long-haul flights, can also increase the risk of developing a blood clot. You can find out more about how to reduce your risk of DVT when travelling on the NHS Choices website.
- heart disease and diabetes
- a previous history of blood clots
- being overweight
You can help reduce your risk of developing a blood clot by regularly taking short walks or doing simple leg and foot exercises.
Take particular care on long-haul flights or on a lengthy car journey.
During a flight, you can try to walk around the cabin regularly and during a car journey stop hourly and walk around. Wear loose clothing and keep drinking plenty of water to keep well hydrated.
Blood clots are usually treated with drugs that thin the blood (anticoagulants). This will be given as an injection at first then may be changed to a tablet. You may stay on the tablets for a number of months and you'll have regular blood tests.
If you’re having an operation, you may be advised to stop taking particular medicines for a period of time before surgery. If you need to stay in hospital, your risk of developing a blood clot should be assessed and you may be given anti-embolism or compression stockings to wear to ‘squeeze’ the lower leg, helping the blood return towards the heart. In some situations, for example straight after surgery, a device (called an intermittent compression system) is used to do this for a short time.
If you think you may have a blood clot contact your treatment team, local A&E department or GP as soon as possible.