Introduction

Leukemia is cancer of the blood cells, usually the white blood cells. Chronic lymphocytic leukemia is also known as chronic lymphoid leukemia, chronic lymphoblastic leukemia, and CLL. CLL is the most common type of leukemia in adults. About 14,990 new cases of CLL were diagnosed in the United States in 2010, according to the American Cancer Society. The disease usually occurs in older adults and is very rare in people under age 40. More than half the people with CLL are over 70.

The tissues and organs that produce, store, and carry white blood cells that fight infections and other diseases make up the body’s lymph system. CLL occurs when bone marrow and the lymph system produce too many lymphocytes. Lymphocytes are white blood cells that fight infection by making antibodies that attack harmful organisms. A person with CLL has lymphocytes that cannot function properly to fight infection. They crowd out other blood cells and may collect in blood, bone marrow, lymph tissue, and spleen, producing enlargement of lymph nodes and spleen.

CLL is a “chronic” leukemia because it gets worse slowly and people with CLL might not have any symptoms. As the diseases progresses, the shortage of red blood cells (known as anemia) can cause shortness of breath, fatigue, pale skin, and other problems. Without enough mature white blood cells, many patients with CLL have frequent infections. Because the white blood cells in CLL also crowd out blood platelets, which prevent and control bleeding, some people with CLL bruise and bleed easily.

The causes of CLL are not known. However, people who are middle-aged, white, or older males have a slightly higher chance of getting CLL. People whose family members have had CLL or cancer of the lymph system are also at slightly higher risk of having CLL.