Types and risk groups of acute myeloid leukaemia (AML)

Acute myeloid leukaemia (AML) is divided into different groups (subtypes) using the World Health Organization (WHO) classification system. It is also divided into risk groups based on genetic changes and other factors. These risk groups look at the risk of the leukaemia coming back (relapse).

Your healthcare team plan your treatment according to the particular type and risk of AML you have.

Finding the type of AML

You have several laboratory tests using blood, bone marrow and tissue samples. The results help your doctor work out your type of AML.

Your doctor first looks at your leukaemia cells under a microscope. This is called a blood film or a blood smear. 

They also do some more detailed tests on the leukaemia cells, including looking for:

• proteins on the surface of leukaemia cells (immunophenotyping)
• gene and chromosome changes

Immunophenotyping tests

This is testing for proteins made by some types of leukaemia cells.

Gene and chromosome changes

You have tests to look for chromosome (genetic) changes inside the leukaemia cells. These tests are also called chromosome analysis, cytogenetic tests or molecular analysis.

A specific type of cytogenetic test they use is fluorescence in situ hybridisation (FISH). The FISH technique uses a special fluorescent dye. This makes it easier to see particular gene and chromosome changes.

Next generation sequencing (NGS) is another type of test to look for specific changes in genes that might be causing AML. This is important in AML because your doctor may be able to recommend treatment that targets these changes.

There are many possible genetic changes that your doctor looks for. Examples include:

• NPM1
• CEPBA
• TP53
• ASXL1
• MECOM
• NUP98
• KMT2A

The World Health Organization (WHO) system

The World Health Organisation (WHO) classification system divides AML into groups according to the type of myeloid cell that has become abnormal and:

• whether there are specific genetic changes in the cells
• how different the myeloid cells look under a microscope compared to normal cells (differentiation)
• whether your leukaemia developed from a group of blood cancers called myelodysplasic syndrome

WHO also look at whether AML developed after treatment for another cancer or condition. Or whether the AML developed from a fault in the genes you have inherited from your parents (germline predisposition). These are grouped as secondary myeloid neoplasms.

There are 3 main groups:

• AML with defining genetic abnormalities
• AML defined by differentiation
• myeloid sarcoma

Each of these groups have their own subtypes. This system is quite complicated and not covered in detail here. Your healthcare team can explain the type you have and what this means.

Acute promyelocytic leukaemia (APL) is a subtype of AML and is treated quite differently to other types of AML. We have separate information about this type of AML.

Risk stratification

Doctors also put AML into groups called favourable risk, intermediate risk, and adverse risk. Your doctor decides on your risk depending on:

• how well they think treatment will work
• the risk of your leukaemia coming back

This helps them plan the most effective treatment for you.

Risk groups depend on many factors including:

• your type of AML

• changes in chromosomes and genes

• markers on leukaemia cells

• your white blood cell count when you are diagnosed

• your age at diagnosis

• whether your AML has developed from a group of blood cancers such as myelodysplastic syndrome

• whether your leukaemia is linked to treatment for an earlier cancer or condition

• whether there are any leukaemia cells in the central nervous system

Your risk group might change as you go through treatment. Your healthcare team can explain this more.

Favourable risk 

Standard treatment (glossary) generally works well for people in this risk group. They have a higher chance of their leukaemia going into remission (glossary) and staying in remission. People usually have chemotherapy.

Intermediate risk 

People in this group have genetic and chromosomal changes that do not fit easily into the favourable and adverse groups. Doctors may look at other factors such as age and overall health to decide on treatment. People usually have chemotherapy. They may then have more intense treatment depending on their situation. 

Adverse risk 

People in this risk group have a greater risk of their leukaemia coming back (relapsing) or not responding to treatment. They usually have more intense treatment. For example, high dose chemotherapy followed by a donor stem cell transplant. They may have treatment as part of a clinical trial.

Coping and support

Coping with a diagnosis of AML can be overwhelming. There is help and support available to help you and your friends and family.