What Is Chronic Lymphocytic Leukemia?

This content has been reviewed and approved by

Hagop M. Kantarjian, MD
Chairman & Professor, Leukemia Department
MD Anderson Cancer Center
University of Texas

Chronic lymphocytic leukemia (CLL) is a cancer of the blood in which too many lymphocytes, a type of white blood cell, are produced by the bone marrow and by organs of the lymph system. Lymphocytes normally fight infection by making antibodies that attack foreign proteins.

CLL is the most common adult leukemia. About 14,990 new cases of CLL will be diagnosed in the United States in 2010, according to the American Cancer Society. The disease usually occurs in individuals between 65 and 80 years old.

If you have CLL, your lymphocytes are overabundant and many are immature. They are not able to fight infections. They crowd out other blood cells and may collect in blood, bone marrow, lymph tissue, and spleen. CLL is a slowly progressing disease.

CLL can also result in the destruction of red blood cells, leaving you with too few of them.

Like most cancers, early detection and treatment can help control the disease or eliminate it from your body.