What is acute lymphoblastic leukaemia?
Acute lymphoblastic leukaemia (ALL) is a blood cancer.
The three main types of blood cells have specific functions:
- white blood cells – fight infection
- red blood cells – carry oxygen around the body
- platelets – help the blood clot.
ALL develops when the body has too many of the white blood cells known as lymphoid blast cells, also called lymphoblasts. ALL is also sometimes called acute lymphatic leukaemia.
The abnormal blast cells are known as leukaemia cells. Because the leukaemia cells are immature and abnormal, they don’t carry out the usual infection-fighting function of white blood cells. They also crowd out normal white blood cells, which then can’t work properly. This increases the risk of infections.
When the bone marrow fills with leukaemia cells, there is little room for healthy red cells and platelets to be produced. This can cause fatigue, bleeding problems and other health issues.
Learn more about:
- The difference between acute and chronic leukaemia
- The difference between ALL and AML
- What causes ALL
- Who gets ALL
- The blood
What is the difference between acute and chronic leukaemia?
While all types of leukaemia start in the bone marrow and affect white blood cell production, they are grouped according to which type of white blood cell is affected (lymphoid or myeloid), whether there are abnormalities in the bone marrow, and how quickly the disease develops.
Acute leukaemia
This usually affects immature cells, occurs suddenly, and develops quickly. There are two types of acute leukaemia:
- acute lymphoblastic leukaemia (ALL)
- acute myeloid leukaemia (AML).
Chronic leukaemia
This usually affects more mature cells, appears gradually, and develops slowly over months to years. There are two types of chronic leukaemia:
- chronic lymphocytic leukaemia (CLL)
- chronic myeloid leukaemia (CML).
What is the difference between ALL and AML?
ALL stands for acute lymphoblastic leukaemia (sometimes called acute lymphatic leukaemia), and AML stands for acute myeloid leukaemia. These are the two main types of acute leukaemia. The difference between them is the type of white blood cells affected.
| ALL | AML | |
| White blood cells affected | The body has too many of the white blood cells known as lymphoblasts. | The body has too many of the white blood cells known as myeloblasts. |
| Subtypes | ALL can develop from B-cells or T-cells, which are different types of lymphocytes. The main subtypes of ALL are B-cell ALL, T-cell ALL and mixed lineage ALL. | There are different subtypes of AML, including a subtype known as acute promyelocytic leukaemia (APML) that is treated differently. |
| More information | Learn more about ALL risk factors, causes, symptoms, diagnosis and treatment. | Learn more about AML risk factors, causes, symptoms, diagnosis and treatment. |
What causes ALL?
The exact causes of acute leukaemia are not yet understood, but a number of factors are known to increase the chance of developing the disease, including:
- previous treatment with chemotherapy or radiation therapy
- having certain genetic disorders, such as Down syndrome
- exposure to high levels of radiation (e.g. nuclear accident)
- exposure to some chemicals, such as benzene, petroleum products, paints, certain pesticides and heavy metals, over a long period of time.
In addition, some viruses (e.g. Epstein-Barr virus) increase the risk of ALL.
Who gets ALL?
Each year in Australia, more than 3700 people are diagnosed with a form of leukaemia, and it is the most common type of cancer diagnosed in people under 24. About 1400 of these cases are acute leukaemia, accounting for about 1.1% of cancer cases in Australia, so overall, acute leukaemia is rare.
Acute lymphoblastic leukaemia (ALL) – About 370 people are diagnosed each year. Of these, more than 200 are children under 15. ALL mostly occurs in children 1–4 years old.
Acute myeloid leukaemia (AML) – This is the most common type of acute leukaemia in adults, with about 1050 people diagnosed each year. It becomes more common with age and mostly occurs after 65.
The blood
Blood is pumped around your body to provide oxygen and nutrients to your tissues, and to remove waste products. It is made up of blood cells carried in a clear fluid called plasma.
All three types of blood cells have a limited life span and need to be continually replaced. Most are made in the bone marrow, which is the spongy part in the centre of the bones.
The bone marrow contains stem cells. These are unspecialised blood cells that first develop into immature cells known as blast cells. Normally, the blast cells then become mature red or white blood cells or platelets and carry out their set functions.
There are two families of stem cells:
- lymphoid stem cells – develop into lymphoblast cells and then into lymphocytes, which are a type of white blood cell
- myeloid stem cells – develop into myeloblast cells and then into red blood cells, most types of white blood cells, and platelets.
If lymphoblast or myeloblast cells do not mature properly or if there are too many in the blood, it can cause leukaemia.
Dr Anoop Enjeti, Senior Staff Specialist Haematologist, Calvary Mater Newcastle, and Conjoint Senior Lecturer, The University of Newcastle; Ray Araullo, Deputy Head, Social Work Department, Royal North Shore Hospital; Shehaan Fernando, Consumer; Narelle Greentree, Clinical Nurse Specialist, Hunter Haematology Unit, Calvary Mater Newcastle; Yvonne King, 13 11 20 Consultant, Cancer Council NSW; Karen Maddock, Haematology Clinical Nurse Consultant, Westmead Hospital; Melanie Sexton, Consumer; Dr Jonathan Sillar, Haematology Registrar, Calvary Mater Newcastle, and Conjoint Fellow, The University of Newcastle.
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