Chronic Lymphocytic Leukemia
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NORD is very grateful to Jennifer R. Brown, MD, PhD, Director, CLL Center, Dana-Farber Cancer Institute, Assistant Professor of Medicine, Harvard Medical School, for the assistance in the preparation of this report.
Synonyms of Chronic Lymphocytic Leukemia
- chronic lymphoid leukemia
- SLL (small lymphocytic lymphoma)
- Ig-mutated CLL
- Ig-unmutated CLL
Chronic lymphocytic leukemia (CLL) is a malignant blood disorder in which there are an increased number of white blood cells in the lymphoid tissue. In CLL, the abnormal lymphocytes, also called leukemic cells, are produced instead of healthy white blood cells, and then accumulate over time. As the number of unhealthy blood cells grows, there is less room for healthy cells. The combination of fewer healthy cells, and the fact that the CLL lymphocytes are poor at fighting infections can lead to frequent infection, anemia, and easy bleeding. This disease progresses slowly, and the uncontrolled buildup and enlargement of lymphoid tissue can occur in various sites of the body such as the lymph nodes, spleen, bone marrow, and lungs. CLL is the most common type of leukemia in adults and very rarely occurs in children.
In the majority of cases, chronic lymphocytic leukemia is the result of a rapid production of B lymphocyte cells (a short-lived type of white blood cell that is responsible for the production of vertebrate serum proteins that include antibodies). What was previously called CLL derived from T lymphocytes has been renamed as another disorder, T cell prolymphocytic leukemia. The overgrowth of cells in this T-cell disease tends to be much faster.
The ability to distinguish between cells that have unmutated IgVH (Ig-unmutated CLL) and mutated IgVH (Ig-mutated CLL) has become very important in predicting the course of the disease (prognosis). Patients who have Ig-unmutated CLL have a much shorter average survival period of about 7 years compared to Ig-mutated CLL patients, whose average survival period is about 25 years. These survival times however are based on older data and likely longer now, with improved therapies. A protein called ZAP-70 is correlated with the IGVH status about 75% of the time but also provides independent prognostic information. Determining the subset of CLL based on IGVH status is important because it predicts prognosis. Because CLL usually progresses so slowly, many patients do not need immediate treatment and some do not even require it in their lifetime. Treatment is still based primarily on symptoms or worsening blood counts, not on these prognostic factors.
Chronic Lymphocytic Leukemia Resources
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