A study comparing a blood thinning injection with a blood thinning tablet for people with cancer who have a blood clot (select-d)

Cancer type:

All cancer types





This study is comparing 2 types of treatment for blood clots in people who have cancer. It is also looking into the best length of time to have the treatment for.

Blood clots (thrombosis) are more common in people who are having (or have had) treatment for cancer. Doctors think that cancer cells can release chemicals which make the blood thicker than usual, and so more likely to form a clot. A blood clot in an arm or leg is called a deep vein thrombosis or DVT. It can cause redness, pain and swelling. If bits of the clot break off and are carried to the lungs, they can cause a blockage called a pulmonary embolism or PE. You may have a sudden cough, chest pain or breathlessness. The clots need treatment as some may be life threatening.

If you have a blood clot, you may have a blood thinning injection called dalteparin, or Fragmin. This helps to dissolve the clot and stop others forming.

In this study, researchers want to compare this with a blood thinning tablet called rivaroxaban.

The aims of this study are to see

  • If rivaroxaban is as good as dalteparin at treating clots and stopping new clots forming
  • If it is better to have treatment for 6 months or 12 months

You may not get any direct benefit from taking part in this study. But the results will be used to help people with cancer in the future.

Who can enter

You may be able to enter this study if you have been in one of the following situations in the last 6 months

And you

  • Have a blood clot in your leg that is causing symptoms, or a blood clot in your lungs
  • Are well enough to be up and about for at least half the day (performance status 0, 1 or 2)
  • Have satisfactory blood test results
  • Are willing to use reliable contraception during treatment and for 6 months afterwards if there is any chance that you or your partner could become pregnant
  • Are at least 18 years old

You cannot enter this study if you

  • Are taking any blood thinning drugs (unless this is medication you started to try to prevent a blood clot) - please note, you should not stop taking any medication without checking with your doctor
  • Are taking more than 75mg aspirin each day
  • Would be starting study treatment more than 72 hours after being diagnosed with a blood clot
  • Have a type of liver disease such as hepatitis or scarring of your liver (cirrhosis)
  • Have an infection of the inner lining of your heart
  • Can’t take medication to thin your blood as you have a condition that is making you bleed at the moment, or you bleed very easily
  • Have high blood pressure (higher than 180 over 110) – if your blood pressure is well controlled with tablets you may still be able to take part
  • Are taking medication that may affect the study treatment in some way – you can ask your doctor about this
  • Are pregnant or breastfeeding


Trial design

This pilot study will recruit 530 people. It is split into 2 parts. Part 1 is comparing dalteparin injections with rivaroxaban tablets. Part 2 will recruit people who joined the study because they had a blood clot in their lung and people who still have a blood clot in their leg after finishing 6 months of treatment.

The first part of the study is randomised. Everybody taking part will be put into 1 of 2 groups by a computer. Neither you nor your doctor will be able to decide which group you are in.

If you are in group 1, you have dalteparin as an injection under the skin. You have dalteparin once a day for 6 months. A nurse can give this to you at home, or show you or a carer how to give it.

If you are in group 2, you take rivaroxaban tablets every day for 6 months.

Towards the end of treatment, everyone with a DVT will have a type of ultrasound scan to see if it has gone. If it has, you complete your 6 months of treatment.

If you still have a DVT, or if you joined the study because you had a blood clot in your lungs, you go on to part 2 of the pilot study.

Part 2 is also randomised. The people taking part will be put into 1 of 2 new groups by a computer. Neither you nor your doctor will be able to decide or know which group you are in. This is called a double blind trial.

If you are in group 1, you take dummy tablets (a placebo) Open a glossary item for 6 months

If you are in group 2, you take rivaroxaban tablets for 6 months.

10675 Diagram

The study team will ask you to fill out a questionnaire before you start treatment, every 3 months for the first year and then at 18 months and 2 years. The questionnaire will ask about side effects and how you’ve been feeling. This is called a quality of life study. You will also fill out questionnaires asking about whether the clot and its treatment has affected your finances.

The team will also collect information from your medical notes to see how you are getting on.

The team will ask if you would be willing to give up to 4 blood samples for the study. And, to give them permission to store any pieces of tissue or cancer that you may have had removed during any cancer surgery. You do not have to agree to this if you don’t want to. You can still take part in the main pilot study.

Hospital visits

You see the study team 3 times in the first month, and then at

  • 3 months
  • 5½ months
  • 9 months
  • 12 months
  • 18 months
  • 2 years

You have blood tests at some of these appointments.

If you have a blood clot in your leg, you also have a scan after 5 months of treatment to see if your blood clot has gone. You go to hospital for the scan.

Side effects

The side effects of dalteparin and rivaroxaban are similar. The most serious one to look out for is bruising or bleeding. The team will tell you what you need to look out for, and who to contact if you have problems.

If you have any bleeding that will not stop or is not normal for you – such as a severe nose bleed or blood when you cough or go to the toilet – you must tell your nurse or doctor straight away.

The dalteparin injection might sting a little bit.


Barrow in Furness
Burton on Trent
Great Yarmouth
Kingston upon Thames
Milton Keynes
Newcastle upon Tyne
North Shields
South Shields
St Helens
Weston Super Mare

Recruitment start:

Recruitment end:

How to join a clinical trial

Please note: In order to join a trial you will need to discuss it with your doctor, unless otherwise specified.

Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Chief Investigator

Professor Annie Young

Supported by

Experimental Cancer Medicine Centre (ECMC)
University of Warwick
Warwick Medical School Clinical Trials Unit

Questions about cancer? Contact our information nurses

Freephone 0808 800 4040

Last review date

CRUK internal database number:


Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Charlie took part in a trial to try new treatments

A picture of Charlie

“I think it’s really important that people keep signing up to these type of trials to push research forward.”

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