Chronic lymphocytic leukemia (CLL) — also called small lymphocytic leukemia — is the most common type of chronic leukemia in adults. It occurs when the bone marrow contains too many of the cells that will eventually turn into lymphocytes (specific types of white blood cells). This can happen because the body produces too many of the cells and/or because abnormal cells don’t die off when they should.
Healthy lymphocytes are an important part of the immune system, producing the antibodies your body needs to protect you from infection. But the abnormal lymphocytes associated with CLL don’t produce those antibodies, so you may begin to get sick more often.
They also begin to destroy red blood cells (which carry oxygen throughout the body) and platelets (which cause the blood to clot after an injury). That’s why you may feel fatigued, become anemic, or experience frequent bruising or bleeding. The abnormal cells begin to fill up the marrow, crowding out healthy blood cells.
Slow-Growing and Fast-Growing CLL
In most cases, CLL grows slowly and may not require treatment right away. Early in the disease, the leukemic cells can still do some of the work of normal white blood cells, so you may not have symptoms at first. Doctors often discover chronic leukemia during a routine checkup, before any symptoms develop.
However, as the number of leukemia cells in the blood increases, you will begin to experience such symptoms as swollen lymph nodes or infections. When symptoms do appear, they are usually mild at first, but gradually they will get worse. CLL that grows quickly needs to be treated promptly.
Most CLL patients are over age 55; it almost never affects children. About 16,000 new cases of CLL are diagnosed each year.
Why is CLL treated by the Lymphoma team?
Lymphomas are cancers that begin in the lymphocytes — a subtype of white blood cells that are part of the immune system. They usually affect the lymph nodes and other tissues. Chronic lymphocytic leukemia (CLL) begins in mature B-cell lymphocytes, but it is classified as a leukemia because the abnormal cells are found mostly in the blood and bone marrow. (However, the cells can also nest in other organs of the immune system, such as lymph nodes and the spleen.) Because CLL involves lymphocytes, it is treated by the team that specializes in cancers affecting those cells.