- Chronic lymphocytic leukaemia (CLL)
Chronic lymphocytic leukaemia (CLL)
What is chronic lymphocytic leukaemia?
Chronic leukaemia is a blood cancer that develops when the body makes too many abnormal white blood cells (blast cells). These abnormal blast cells are known as leukaemia cells.
Because leukaemia cells live too long or multiply too quickly, large numbers of them circulate in the blood. They crowd out normal white blood cells and, because they don’t fight infection, they increase the risk of infection.
As leukaemia progresses, the bone marrow fills with leukaemia cells and there is less room for healthy red cells and platelets. This may cause various health problems, such as tiredness, dizziness, bleeding problems and bruising.
Learn more about:
- Is it different to acute leukaemia?
- What are CLL and CML?
- Who gets CLL
- What causes CLL
- Blood cells and leukaemia cells
- The lymphatic system
Is it different to acute 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.
Chronic leukaemia usually affects partly immature cells, appears gradually, and develops slowly over months to years.
Acute leukaemia affects fully immature cells, occurs suddenly, and develops quickly.
What are CLL and CML?
CLL and CML are the two main types of chronic leukaemia. The difference between them is in the type of white blood cell that is affected.
Chronic lymphocytic leukaemia (CLL)
In CLL, the body has too many of the white blood cells known as lymphocytes. The lymphocytes are part of the lymphoid family of blood cells. This disease is also called chronic lymphatic leukaemia.
Chronic myeloid leukaemia (CML)
In CML, the body has too many of the white blood cells known as granulocytes. The granulocytes are part of the myeloid family of blood cells. This disease is sometimes called chronic granulocytic leukaemia.
Small lymphocytic lymphoma (SLL)Small lymphocytic lymphoma (SLL) has traditionally been classed as a non-Hodgkin lymphoma. However, it is now considered to be the same disease as CLL and is treated in a similar way.
Both SLL and CLL are diseases of the lymphocytes, but in SLL the abnormal lymphocytes are mainly in the lymph nodes, while in CLL they are mainly in the blood and bone marrow. Some doctors may refer to small lymphocytic lymphoma as CLL/SLL.
Who gets CLL?
Each year in Australia, about 3900 people are diagnosed with a form of leukaemia, and more than 1900 of these cases are chronic leukaemia.
CLL is the most common type of chronic leukaemia, with about 1600 people diagnosed each year. It is twice as likely to occur in men as in women and almost never occurs in children.
What causes CLL?
Chronic leukaemia is caused by changes to one or more of the genes (DNA) that control the growth and development of blood cells. These changes happen over time, but it is not known why they occur in some people and not others. The exact cause of CLL is not yet understood.
Some people have genetic abnormalities that can lead to CLL. These genetic defects are not usually inherited, but there are rare cases where CLL may occur more commonly in families. If you are worried about this, talk to your doctor, who may refer you to a genetic counsellor.
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.
There are three main types of blood cells: white blood cells, red blood cells, and platelets. Each type has a specific job to do:
|White blood cells – fight infection.|
|Red blood cells – carry oxygen around the body.|
|Platelets – help the blood clot.|
All 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 bones.
Bone marrow contains blood stem cells. These are unspecialised blood cells that first turn into immature cells known as blast cells. Normally, the blast cells become mature white or red blood cells or platelets. If white blood cells do not mature properly or if there are too many in the blood, it can cause leukaemia.
There are two families of blood stem cells: lymphoid and myeloid (see diagram below). These lead to different types of white blood cells and can be affected by different types of leukaemia.
Blood cell families
Stem cells divide into two families (lymphoid or myeloid), then become immature cells (lymphoblast or myeloblast cells). If cells are normal, they develop into different kinds of mature blood cells.
The lymphatic system
The lymphatic system works with the white blood cells to protect the body against infection. A large network of thin tubes (lymph vessels) carries a clear fluid called lymph.
The lymph travels to and from areas of lymph tissue, including the lymph nodes, spleen and liver. When leukaemia causes abnormal white blood cells to build up, the lymph tissue becomes swollen.
|Lymph nodes||Also known as lymph glands, these small, bean-shaped structures are found in the neck, underarms, chest, abdomen and groin. The lymph nodes filter out toxins and help fight infections, and also produce some blood cells.|
|Spleen||This is an organ on the left side of the body under the ribs. It clears out old damaged blood cells.|
|Liver||This large organ removes toxins, controls sugar levels, and stores vitamins.|
Diagram of the lymphatic system
Download a PDF booklet on this topic.
Dr Kate Melville, Haematology Staff Specialist, Calvary Mater Newcastle, and Conjoint Lecturer, The University of Newcastle; Karl Jobburn, Clinical Nurse Consultant, Haematology, Liverpool Hospital; Patricia Masters, Consumer; Karen Robinson, 13 11 20 Consultant, Cancer Council NSW; Dr Emma Verner, Staff Specialist, Haematology, and Medical Director, Bone Marrow Transplant and Apheresis Unit, Concord Hospital, and Clinical Senior Lecturer, The University of Sydney.
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