Chronic lymphocytic leukaemia (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.

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.

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.

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.