Blood clots in a vein and pancreatic cancer

What is a blood clot?

Normally when you cut yourself, your blood clots to form a scab over the cut and stop the bleeding. Sometimes a blood clot forms in a vein, which is not normal. This often happens in the leg (calf or thigh) or arm. With pancreatic cancer it may also happen in veins near the pancreas such as the splenic or portal vein.

This is called a deep vein thrombosis (DVT), and it can block the normal flow of blood through the veins. Part of the clot may break off and travel to the lungs, where it can cause a blockage, usually in an artery. This is called a pulmonary embolism (PE), which can be very serious.

A blood clot is serious and needs to be treated straight away.

There are ways to reduce your risk of a blood clot. Most blood clots can be successfully treated with blood thinning (anticoagulant) medicines.

Why does pancreatic cancer cause blood clots?

There is a higher risk of getting a blood clot if you have cancer. If you have pancreatic cancer the risk is even higher, and people with advanced (metastatic) pancreatic cancer are more at risk.

There are many reasons for this.

• The cancer itself can increase the risk of a blood clot. This may be because the cancer cells release substances that make your blood more likely to form clots.
• Some cancer treatments may increase your risk. These include some chemotherapy drugs or surgery to remove the cancer.
• Moving around less after surgery or treatment can also increase your risk of a blood clot.

Your risk may also be higher if you:

• have an inherited condition that makes blood clots more likely, such as Factor V Leiden
• use hormone replacement therapy (HRT) or a contraceptive pill that contains oestrogen
• have varicose veins (swollen veins)
• have had a blood clot before, or a close relative has
• are over 60
• are obese
• or you smoke.

How can I reduce my risk of a blood clot?

Speak to your medical team about your risk of getting a blood clot and what you can do to help reduce it.

• This might include keeping as active as you can and moving your legs when sitting down.
• Try to drink plenty of fluids, as you are more likely to get a clot if you are dehydrated.
• If you are having surgery or chemotherapy, your medical team may also recommend things to reduce your risk of a blood clot.

How can I reduce my risk of a blood clot if I go into hospital?

If you are staying in hospital you will move around less, which increases the risk of a blood clot. You should be given information about how to reduce the risk, and your medical team should check for blood clots regularly. You may be given surgical stockings to wear to improve the blood flow in your legs. You will probably also be given medicine to thin the blood, which helps reduce your risk of a clot.

The medical team will get you moving as soon as possible. If you are not able to move around much, there are exercises you can do in bed. These include simple foot exercises, such as bending and straightening your toes. Try to drink enough fluids.

If you have any symptoms that might be a sign of a blood clot, tell the medical team straight away.

How can I reduce my risk of a blood clot if I’m having chemotherapy?

If you are having chemotherapy, your oncologist (cancer doctor) should consider whether you need blood thinning medicine to reduce the risk of clots. If you are given this, you will take it for as long as your chemotherapy lasts, or longer if your oncologist thinks you need it.

If you are already taking blood thinning medicine your oncologist will check that it’s suitable while you are having chemotherapy, and may change it.

You should be given information on ways to reduce the risk of a blood clot. Try to move around as much as possible, and drink plenty of fluids. If you have any symptoms that might be a sign of a blood clot, call the 24 hour emergency number you were given when you started chemotherapy. If you can’t get through on the emergency number, go to A&E or call 999.

How can I reduce my risk of a blood clot if I’m having radiotherapy?

If you are having radiotherapy for pancreatic cancer, you will not normally get medicine or surgical stockings to reduce the risk of clots. Radiotherapy doesn’t increase the risk of getting a blood clot.

How is a blood clot diagnosed?

If your doctor thinks you have a DVT, you will usually have an ultrasound scan of the affected area. This is called a ‘Doppler’ and looks at the flow of blood through blood vessels.

If your doctor thinks you have a pulmonary embolism, you may have a computed tomography pulmonary angiogram (CTPA). This is a type of X-ray that looks for a blood clot in the blood vessels in the lungs.

How is a blood clot treated?

Blood clots can usually be treated without stopping your cancer treatment. If you get a blood clot you will probably be given blood thinning medicines. You may hear these called anticoagulant medicines.

There are different types of blood thinning medicines.

• Direct oral anticoagulants (DOACs) are tablets, usually taken once a day. Examples are rivaroxaban and edoxaban.
• Low molecular weight heparins (LMWHs) are medicines given once or twice a day as a small injection into the tummy (abdomen). Examples are enoxaparin and dalteparin.

You will have blood thinning medicine for three to six months at first. Your doctor will then review your treatment, to check whether you need to carry on taking it.

There is a risk that you could get a blood clot again after you finish blood thinning treatment. Contact your medical team, go to A&E or call 999 if you get any of the symptoms.

Side effects of blood thinning drugs

The main side effect of blood thinning medicines is bleeding for longer than usual, for example if you cut yourself or have a nosebleed. This is because it will take longer for a normal clot to form to stop the bleeding. You may also find that you bruise more easily.

If you are having injections, you may get bruises in the injection area.

Ask your medical team about the side effects before you start the treatment.

You should be given an information sheet about your blood thinning medicine so you know what to expect. This should include how to take the medicine, the side effects and when to get help. You should also be given an anticoagulant medicines alert card that you should always carry with you.

Published August 2025

Review date August 2028