Chronic lymphocytic leukemia, which is also called CLL, is a kind of cancer that occurs in a specialized white blood cell called a lymphocyte. The cancerous change often takes place in the bone marrow, where all blood cells are made. CLL is slow to develop and may affect a person for many years before symptoms are noticed.

What is going on in the body?

When the cancerous cells grow in the bone marrow, normal bloods cells are often destroyed or crowded out. Having fewer normal white cells can cause the person to become infected easily. The infections may be serious and life-threatening. Having fewer platelets means that the person may bruise or bleed easily. Anemia, or low numbers of red blood cells, can make the person weak and easily tired.

The cancerous white cells can multiply quickly. Then, some of them can leave the bone marrow and travel throughout the body in the bloodstream. This often leads to problems in other parts of the body.

What are the causes and risks of the disease?

No one knows what causes CLL.