Your child will have tests to find the type of cancer and the stage of the cancer, as this may affect how their treatment is planned.

The stage of a cancer means the size of the tumour and whether it has spread beyond where it started in the body. Knowing the extent of the cancer helps the doctors to decide on the best treatment for your child.

Generally, cancer is divided into four stages:

• Stage 1 – small and localised
• Stage 2 or 3 – when the cancer has spread into surrounding structures
• Stage 4 – when it has spread to other parts of the body

If the cancer has spread to distant parts of the body this is known as secondary or metastatic cancer.

There are two main types of leukaemia in children:

• acute lymphoblastic leukaemia (ALL)
• acute myeloid leukaemia (AML).

Each type can be divided into different sub-types. Blood and bone marrow samples will be checked to find out which type of leukaemia a child has. Doctors will look to see exactly which type of cell has been affected (become leukaemic) and at which stage of its development. The cells may be tested with antibodies to see if they have certain proteins on their surface. This is known as immunophenotyping.

Almost all of the cells in our body contain chromosomes. Chromosomes are made up of genes which control the activities of the cell. There are often changes in the structure of the chromosomes (genetic changes) in leukaemia cells. Testing the cells for any genetic changes is known as cytogenetics.

Knowing the exact type of leukaemia helps the doctors to know which treatment is likely to be most effective.