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About acute lymphoblastic leukaemia (ALL)

Find out about acute lymphoblastic leukaemia (ALL) and how common it is.

What is acute lymphoblastic leukaemia (ALL)?

Acute lymphoblastic leukaemia (ALL) is a type of blood cancer that starts from young white blood cells called lymphocytes in the bone marrow. The bone marrow is the soft inner part of the bones, where new blood cells are made.

It usually develops quickly over days or weeks. It is the most common type of leukaemia to affect children but can also affect adults.

How common it is

Acute lymphoblastic leukaemia is rare. In the UK around 760 people are diagnosed each year with acute lymphoblastic leukaemia.

Who gets it

ALL is most often diagnosed in children, teenagers and young adults. The age group with the highest incidence is young children aged 0 - 4 years.

When combining all ages, more than half (53%) of cases are diagnosed in people aged 10 and over each year.

What happens in ALL

The word acute means that the leukaemia can develop fairly quickly. The bone marrow produces white blood cells called lymphocytes too quickly because they grow and divide too fast. These abnormal cells build up in the blood. 

 The leukaemic cells can eventually spread into other parts of the body, including the:

  • lymph nodes
  • liver
  • spleen
  • central nervous system (brain and spinal cord)
  • testicles

The cells can build up in the lymph nodes, bone marrow and spleen and cause swelling. 

 If it wasn't treated the leukaemia would cause death within a few weeks or months. But treatments work very well for most people with ALL.

Blood cells and ALL

To understand how and why leukaemia affects you as it does, it helps to know how you make blood cells.

Your body makes blood cells in the bone marrow. The bone marrow is the soft inner part of your bones. You make blood cells in a controlled way, as your body needs them.

All blood cells start as the same type of cell, called a stem cell. This stem cell then develops into:

  • myeloid stem cells – which become white blood cells called monocytes and neutrophils (a type of granulocyte)
  • lymphoid stem cells – which become white blood cells called lymphocytes
  • erythroblasts – which become red blood cells
  • megakaryocytes – which become platelets

The diagram helps explain this:

Diagram showing how blood cells are made

In acute lymphoblastic leukaemia, the bone marrow makes too many lymphocytes. These lymphocytes are not fully developed and are not able to work normally.

Diagram showing which cell ALL starts in

Types of leukaemia

There are several types and subtypes of leukaemia. The name of the leukaemia you have depends on:

  • how quickly it develops
  • the type of white blood cells it affects

Doctors divide leukaemia into two main groups, acute and chronic. Acute leukaemia develops very quickly. Chronic leukaemia tends to develop slowly, usually over months or years without causing many symptoms.

Doctors divide these groups further, depending on the type of white blood cell they affect.

In acute leukaemia:

  • acute myeloid leukaemia (AML) affects myeloid cells
  • acute lymphoblastic leukaemia (ALL) affects lymphoid cells

In chronic leukaemia:

  • chronic myeloid leukaemia (CML) affects myeloid cells
  • chronic lymphocytic leukaemia (CLL) affects lymphoid cells

How leukaemia affects you

White blood cells help fight infection. But if your body makes abnormal white blood cells, they don’t work properly. So you are more likely to get infections and find it difficult to get rid of them.

Too many white blood cells can overcrowd the bone marrow. So, there isn't enough space for other types of blood cells. Then you might have a lower than normal number of red blood cells and platelets.

Having too few red blood cells makes you tired and breathless (anaemic). And if you don’t have enough platelets, you can have bleeding problems, for example, nosebleeds.

Abnormal white blood cells can build up in parts of the lymphatic system, such as the spleen and lymph nodes, making them swell. They might build up in the liver. This can make your tummy (abdomen) swell and feel uncomfortable. The leukaemia cells can also spread to the brain, and the testicles in men.

Last reviewed: 
05 May 2016
  • Incidence Statistics from Cancer Research UK (Cancer Stats)

  • Cancer and its management (7th edition)
    J Tobias and D Hochhauser
    Wiley-Blackwell, 2015

  • Cancer: Principles and Practice of Oncology (10th edition)
    VT De Vita, TS Lawrence and SA Rosenberg
    Lippincott, Williams and Wilkins, 2015

  • Treatment of Cancer (6th Edition)

    P Price and K Sikora

    CRC Press, 2015

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