1. Overview
  2. What is a blood clot?
  3. The risk of blood clots in people with cancer
  4. Cancer treatments that increase the risk of blood clots
  5. Other factors that can increase risk of blood clots
  6. Treating and preventing blood clots
  7. If you are in hospital
  8. Finding support

1. Overview

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 also increases the risk.

Blood clots can be harmful but are treatable so it’s important to report symptoms as soon as possible.

If you experience any of the following symptoms contact your local A&E department, GP or specialist team straight away.

  • Pain, redness/discolouration, heat and swelling of the calf, leg or thigh.
  • 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.
  • Tightness in the chest.
  • Unexplained cough (may cough up blood).

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2. What is a blood clot?

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). It can happen in any vein but most commonly happens in the legs, thighs or pelvis – you might hear this called deep vein thrombosis (DVT).

A clot can break loose from where it was formed and travel from one location in the body to another. A blood 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).

The risk of developing a blood clot can be reduced by the use of drugs and other measures.

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3. The risk of blood clots in people with cancer

People with 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.

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4. Cancer treatments that increase the risk of blood clots

Some treatments for breast cancer may increase someone’s risk of developing a blood clot. These include:

As cells are destroyed by chemotherapy they can release substances that cause blood clots.

Both surgery and chemotherapy can damage the walls of blood vessels, which can increase the risk of a blood clot developing.

Central lines

A central line is a long intravenous line that is inserted into a large vein and can be used to give chemotherapy or other drugs.

It’s possible for a blood clot to form in a vein at the tip of the line. Drugs may be given to help prevent this.

Inactivity

For some people, their 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. Inactivity increases the risk of a blood clot as the normal action of the leg muscles helps return the blood back towards the heart.

Inactivity on long journeys such as long flights can also increase the risk of a blood clot. You can find out more about how to reduce your risk of DVT when travelling on the NHS Choices website.

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5. Other factors that can increase your risk of developing blood clots

  • Heart disease and diabetes
  • Smoking
  • A history of blood clots
  • Fractures
  • Being overweight

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6. Treating and preventing blood clots

Blood clots are usually treated with drugs that thin the blood (anticoagulants). This will be given as an injection at first then gradually changed to a tablet. You may stay on the tablets for a number of months. During this time you will have regular blood tests.

You can help reduce your risk of developing a blood clot by regularly taking short walks or doing simple leg exercises.

It’s important to drink plenty of water so you are well hydrated.

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7. If you are in hospital

If you need to stay in hospital, your risk of developing blood clots should be assessed. If you are having an operation, you may be advised to stop taking particular medicines for a period of time before surgery.

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 (intermittent compression system) is used to do this for a short time.

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8. Finding support

If you think you may have a blood clot contact your local A&E department, GP or specialist team as soon as possible.

If you’re experiencing general side effects from having cancer or treatment for it, we’re here to help. You can contact our expert team on 0808 800 6000 or find support on our online Forum.

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Last reviewed: November 2016
Next planned review begins 2018

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