Chronic lymphocytic leukemia (CLL) is a cancer that affects a type of white blood cell called a "lymphocyte."
Lymphocytes help your body fight infection. They're made in the soft center of your bones, called the marrow. If you have CLL, your body makes an abnormally high number of lymphocytes that aren't working right.
More adults get CLL than any other type of leukemia. It usually grows slowly, so you may not have symptoms for years.
Some people never need treatment, but if you do, it can...