A trial looking at treatment for adults with primary thrombocythaemia (PT1)

Please note - this trial is no longer recruiting patients. We hope to add results when they are available.

Cancer type:

Blood cancers




Phase 3

This trial is looking at treatment to control symptoms of primary thrombocythaemia (PT).

Primary thrombocythaemia is a condition which causes too many platelets to be made in the bone marrow. It increases the risk of developing blood clots or having a stroke. There is a small chance that primary thrombocythaemia may develop into a cancer of the white blood cells (leukaemia).

Doctors can treat PT with drugs such as aspirin and a drug called hydroxycarbamide (used to be called hydroxyurea).

The aim of this trial is to follow people who have been diagnosed with PT and collect information about the condition and the side effects of treatment.

Who can enter

You can enter this trial if you:

  • Have been diagnosed with primary thrombocythaemia
  • Have no other blood or bone marrow disorders
  • Are prepared to use reliable contraception throughout the trial if there is any chance that you or your partner could become pregnant
  • Are at least 18 years old

You cannot enter this trial if you:

  • Are pregnant or breastfeeding
  • Have any other serious medical condition
  • Are older than 40 years of age

Trial design

This trial will recruit about 1,600 patients over several years. The trial started with 3 groups - low risk, intermediate risk and high risk. You are put into a group according to your age, which affects your risk of developing a blood clot.

After the high and intermediate risk groups stopped recruiting patients, the trial carried on recruiting people who were classified as having low risk PT for longer. They were under the age of 40.

Earlier in the trial, some of the people in the intermediate risk group had hydroxycarbamide and some people in the high risk group had a drug called anagrelide. The treatment for people taking part with low risk PT was aspirin. You take this as a tablet each day.

Hospital visits

Before you start treatment, you will see the trial doctors and have some tests. The tests include

You will have regular blood tests and the trial doctors will take a swab from the inside of your mouth once a year.

You may have another bone marrow test every 3 years. And you will have follow up appointments for about 5 years.

Side effects

All drugs have side effects. At the dose used in this trial, aspirin has few side effects - but it should not be taken regularly on an empty stomach as it irritates the stomach lining and can cause indigestion and heartburn.

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 Tony Green
Dr Claire Harrison

Supported by

Cambridge University Hospitals NHS Foundation Trust
Cancer Research UK
Experimental Cancer Medicine Centre (ECMC)
Medical Research Council (MRC)
NIHR Clinical Research Network: Cancer
University of Cambridge

Questions about cancer? Contact our information nurses

Freephone 0808 800 4040

Last review date

CRUK internal database number:

Oracle 57

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

Around 1 in 5 people take part in clinical trials

3 phases of trials

Around 1 in 5 people diagnosed with cancer in the UK take part in a clinical trial.

Last reviewed:

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