Chronic lymphocytic leukaemia (CLL)
What is chronic lymphocytic leukaemia?
Chronic lymphocytic leukaemia (CLL) is a type of slow-growing leukaemia that affects developing B-lymphocytes. B lymphocytes (also known as B-cells) are specialised white blood cells. Under normal conditions they produce immunoglobulins (also called antibodies) that help protect our bodies against infection and disease. In people with CLL, lymphocytes undergo a malignant (cancerous) change and become leukaemic cells.
It is important to emphasise that for many people CLL remains stable for many months and years and has little, if any, impact on their lifestyle or general health. Around 30-50% of people diagnosed with CLL never require any treatment for their disease and can survive for many years despite their diagnosis. For others, the leukaemic cells multiply in an uncontrolled way, live longer than they are supposed to and accumulate in the bone marrow, bloodstream, lymph nodes (glands), spleen, liver and other parts of the body. These cells are abnormal and as such are unable to function properly. Over time, an excess number of lymphocytes crowd the bone marrow, and interfere with normal blood cell production.
CLL usually develops slowly and progresses slowly, over months and years. Most people have no symptoms of their disease when first diagnosed. In these cases, people often require no treatment for a long time, apart from regular check-ups with their doctor to carefully monitor their health. Others may need to be treated soon after they are diagnosed.
How common is CLL?
Each year in Australia around 1000 people are diagnosed with CLL. While CLL is a relatively uncommon type of cancer, it is the most common type of leukaemia diagnosed in Australia.
Who gets CLL?
The risk of developing CLL increases with age. Almost 80% of all new cases are diagnosed in people who are over the age of 60. CLL is rare in people under 40 and occurs more frequently in men than in women.
What causes CLL?
The causes of CLL remain unknown but it is thought to result from damage to one or more of the genes that normally control blood cell development. We do know that it is not contagious. Increasingly, it is thought that there may be an inherited tendency to develop CLL in some patients. The risk for developing CLL in a first-degree relative (father, mother, brother, sister or child) of a patient with CLL is approximately seven times higher than the population average. However, as the background risk of developing CLL is very low, the vast majority of family members will never develop CLL. At present, screening for CLL simply because of a family history of the cancer is not recommended.
Like other types of leukaemia, CLL is thought to arise from an acquired mutation (or change) in one or more of the genes that normally control the growth and development of blood cells. This change or changes will result in abnormal growth. The original mutation is preserved when the affected stem cell divides and produces a ‘clone’, i.e. a group of identical cells all with the same defect. As such CLL is regarded as a clonal blood stem cell disorder. Why gene mutations occur in the first place remains unknown but there are likely to be a number of as yet unidentified factors involved. These acquired mutations in genes are gained during a person’s lifetime and are not present at birth and are not passed on to the next generation.
What are the symptoms of CLL?
Because CLL develops slowly many people don’t have any symptoms, particularly in the early stages, and the disease is picked up during a routine blood test.
Other people may visit their GP because they have some troubling symptoms. Symptoms arise from the increasing number of abnormal blood cells in the bone marrow and blood, and the decreasing number of normal blood cells. Possible symptoms may include:
- anaemia, due to a lack of red cells causing persistent tiredness, dizziness, paleness, or shortness of breath when physically active
- increased or unexplained bleeding or bruising, and/or the appearance of red or purple flat pinhead sized purple spots on the skin, especially on the legs initially. These are due to small superficial capillary bleeds known as petechiae (pronounced: pe-tee-chi-a), due to a very low platelet count.
- frequent or repeated infections and slow healing, due to a lack of normal white blood cells
- pain or discomfort under the ribs on the left side, due to an enlarged spleen
- painless swelling of the lymph nodes (glands) in your neck, under your arms or in your groin. This is usually a result of lymphocytes accumulating in these tissues.
- excessive sweating at night
- unintentional weight loss.
Some of the symptoms described above may also be seen in other illnesses, including viral infections. Therefore, most people with these symptoms don’t have leukaemia. However, it is important to see your doctor if you have any unusual symptoms, or symptoms that persist much longer than expected, so that you can be examined investigated properly.