Chronic lymphocytic leukemia (CLL) is cancer of a type of white blood cells called lymphocytes. These cells are found in the bone marrow and other parts of the body. Bone marrow is the soft tissue in the center of bones that helps form all blood cells.
CLL causes a slow increase in a certain type of white blood cells called B lymphocytes, or B cells. Cancer cells spread through the blood and bone marrow. CLL can also affect the lymph nodes or other organs such as the liver and spleen. CLL eventually can cause the bone marrow to lose its function.
CLL; Leukemia - chronic lymphocytic (CLL)
Causes, incidence, and risk factors
The cause of CLL is unknown. There is no link to radiation. It is not clear whether certain chemicals cause CLL. But exposure to Agent Orange during the Vietnam War has been linked to an increased risk of getting CLL.
CLL usually affects older adults, especially those older than age 60. Persons under age 45 rarely get it. CLL is more common in whites than in other ethnic groups. It is more common in men than in women. Some persons with CLL have family members with the disease.
Symptoms usually develop slowly. CLL is often found by blood tests done in people for other reasons or who do not have any symptoms.
Lin TS, Awan FT, Byrd JC. Chronic lymphocytic leukemia. In: Hoffman R, Benz EJ Jr, Silberstein LE, et al., eds. Hematology: Basic Principles and Practice. 6th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 76.
National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology: Non-Hodgkin’s Lymphomas. Version 1.2013. Available at http://www.nccn.org/professionals/physician_gls/pdf/nhl.pdf. Accessed January 2, 2013.
Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Blackman, Stephanie Slon, and Nissi Wang.