What is leukaemia (leukemia)?

Leukaemia (sometimes spelt as leukemia) is a cancer of the blood cells. If you have leukaemia, your body makes some abnormal blood cells. These leukaemia cells behave differently from healthy blood cells.

Different types of leukaemia are named according to:

  • the type of blood cell which is affected
  • whether the leukaemia is acute (faster growing) or chronic (slower growing).

Acute myeloid leukaemia (AML)

Acute myeloid leukaemia (AML) is a rare cancer of blood cells. It affects a type of cell called myeloid stem cells. AML can cause symptoms very quickly and usually needs to be treated as soon as possible after diagnosis.

Acute lymphoblastic leukaemia (ALL)

Acute lymphoblastic leukaemia (ALL) is a rare cancer of white blood cells. It affects a type of cell called lymphoid stem cells. ALL can cause symptoms very quickly and usually needs to be treated as soon as possible after diagnosis.

Chronic lymphocytic leukaemia (CLL)

Chronic lymphocytic leukaemia (CLL) is the most common type of leukaemia. It affects a type of cell called lymphoid stem cells. It develops slowly and often causes no symptoms to start with.

Chronic myeloid leukaemia (CML)

Chronic myeloid leukaemia (CML) is a rare cancer of white blood cells. It affects a type of cell called myeloid stem cells. It usually develops very slowly. For most people, CML can be well controlled and they will live a normal lifespan.

Symptoms of leukaemia (leukemia)

Chronic leukaemias develop slowly and many people have no symptoms in the early stages. It may be discovered by chance after a routine blood test.

Acute leukaemias are more likely to cause symptoms that appear over a few weeks, and people often feel ill quite quickly.

We have more information about the possible symptoms of acute and chronic leukaemia.

Causes of leukaemia (leukemia)

Doctors do not know the exact causes of leukaemia. But there are some risk factors that may increase the chance of developing it. Different types of leukaemia have different risk factors. Having 1 or more risk factors does not mean you will get leukaemia.

We have more information about:

Diagnosis of leukaemia (leukemia)

Some people are diagnosed with leukaemia after being taken to hospital with symptoms that have developed quickly. Others go to see their GP about symptoms. If it is possible you have leukaemia, you will see a doctor who specialises in diagnosing and treating blood problems. This doctor is called a haematologist.

We have more information about:

Treatment for leukaemia (leukemia)

A team of specialists will meet to discuss the best possible treatment for you. This is called a multidisciplinary team (MDT).

Your treatment will depend on different things, such as the type of leukaemia you have and your general health. You may have a combination of treatments.

If you have an acute leukaemia you usually need treatment straightaway. You often start by having intensive chemotherapy.

Some people with chronic leukaemia may not need treatment straightaway and can be monitored. Others may have treatment with a targeted therapy drugs or you may need chemotherapy.

Your doctor or specialist nurse will explain the different treatments and their side effects. They will also talk to you about things to consider when making treatment decisions.

We have more information about:

After leukaemia (leukemia) treatment

What happens after treatment depends on different things, such as the type of leukaemia and treatment you had. Your doctor and nurse will explain more about this and tell you what to expect.

Some people may have on-going treatment with targeted therapy or chemotherapy drugs to keep the leukaemia away.

Each person’s recovery is different. Some treatment side effects may take months to improve. You will have regular check-ups which will include regular blood tests and sometimes other tests. Your check- ups will continue for several years.

You can find out more in our information about:


Useful words to know

When you are dealing with leukaemia, you may come across lots of new words and not know what they mean.

Some of these words are explained here. If you need more information or support, you can call the Macmillan Support Line free on 0808 808 00 00.


Something which develops and progresses quickly.

Blood cells

Cells which are found mainly in the blood. The 3 main types of blood cell are red blood cells, white blood cells and platelets.

Bone marrow

The spongy tissue found inside some of your bones. It is where blood cells are made.


Something which develops slowly.


American spelling of leukaemia.


Different health professionals working together.

Risk factors

Things that can increase your risk of something.

Side effects

Unwanted effects caused by treatment.


Changes in the body that suggest a person may be unwell or have an illness.

About our information

  • References

    Below is a sample of the sources used in our leukaemia (leukemia) information. If you would like more information about the sources we use, please contact us at cancerinformationteam@macmillan.org.uk

    Phelan K and Advani A. Novel therapies in acute lymphoblastic leukemia. Current Hematologic Malignancy Reports. 2018.

    Heuser M et al. Acute myeloid leukaemia in adult patients: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Annals of Oncology, 2020, vol 3, issue 6. Available from www.esmo.org/ [accessed 2021].

    Hochhaus A, Saussele S, Rosti G, et al. Chronic Myeloid Leukaemia: ESMO Clinical Practice Guidelines. Annals of Oncology, 2017; 28 (suppl 4), iv41-iv51. Available from https://www.esmo.org/ [accessed on October 2020].

    Eichhorst B et al. Chronic lymphocytic leukaemia: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. ESMO Guidelines Committee. October 2020.

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editor, Dr Anne Parker, Consultant Haematologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

The language we use

We want everyone affected by cancer to feel our information is written for them.

We want our information to be as clear as possible. To do this, we try to:

  • use plain English
  • explain medical words
  • use short sentences
  • use illustrations to explain text
  • structure the information clearly
  • make sure important points are clear.

We use gender-inclusive language and talk to our readers as ‘you’ so that everyone feels included. Where clinically necessary we use the terms ‘men’ and ‘women’ or ‘male’ and ‘female’. For example, we do so when talking about parts of the body or mentioning statistics or research about who is affected.

You can read more about how we produce our information here.

Date reviewed

Reviewed: 01 March 2022
Next review: 01 March 2025
Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

This means it is easy to use, up-to-date and based on the latest evidence. Learn more about how we produce our information.