Chronic Lymphocytic Leukemia
|Chronic Lymphocytic Leukemia||
Chronic lymphocytic leukemia (CLL), like all leukemias, is a cancer of the blood cells. CLL affects a certain type of white blood cell, called a B lymphocyte. This disease is also called B-cell chronic lymphocytic leukemia. B cells originate in the bone marrow, mature in the lymph nodes, and then circulate in the blood to help fight infections.
In CLL, malignant (cancerous) B cells grow into mature cells, but they don't work properly. These defective B cells fight infections poorly and they can crowd out the normal lymphocytes in the marrow and lymph nodes.
CLL is primarily an adult disease; it is very rare in children and young adults. The median age of diagnosis is 72 years, and about 60% of all people getting CLL are male. In the United States, about 15,000 people are diagnosed with CLL each year. (Data from the National Cancer Institute.)