Doctors use staging systems to assess the extent of the leukaemia and this helps them to know when treatment is needed and which treatment is appropriate for each person.

There are two staging systems commonly used for CLL. They are the Rai and the Binet system. The Binet system is the one most commonly used in the UK.

• Stage A The person has a high white blood cell count, and less than three areas of enlarged lymph nodes.
• Stage B The person has a high white blood cell count and there are three or more areas of enlarged lymph nodes
• Stage C The person has a high white blood cell count; they also have a low red blood cell count, or a low platelet count or both.

The areas of lymph nodes that are counted are the neck, armpits, groin, liver or spleen. If the lymph nodes in both armpits are swollen this is only counted as one area.

Research has shown that CLL stage A does not usually need treatment. With stage B or C, if you are given treatment you will probably have times of remission.

Remission means that you have no symptoms and the number of leukaemic cells in your blood or bone marrow is very low. When the leukaemia begins to develop again, you can be given more treatment.

Eventually, the CLL may become resistant to treatment and it may be harder to get it into remission. At this stage, it may be more difficult for your bone marrow to continue to make all the blood cells you need and you may get infections or have problems with bleeding.

Between 30-50% (3-5 out of ten) of people have a type of CLL which develops extremely slowly and does not usually need treatment.

In people who do not have the genetic variants, the CLL tends to develop more quickly and will usually need to be treated.

You will usually have blood tests to tell whether you have any genetic changes.

In a small number of people with CLL, the leukaemia can suddenly change and start to grow much more quickly. This is called transformation. It can change into another type of leukaemia (prolymphocytic leukemia) or a type of lymphoma (cancer of the lymphatic system) called Richter’s syndrome.

Transformation may be found when you have a blood test - it shows a high number of leukaemia cells.

Sometimes the first sign of transformation may be an increase in symptoms. Symptoms can include a high temperature (fever), weight loss, and a sudden swelling of affected lymph nodes, especially in your abdomen. However, symptoms such as a high temperature and weight loss can occur for many other reasons. It is important to remember that transformation does not happen for most people with CLL.