Chronic lymphocytic leukemia is a type of cancer in which the bone marrow makes too many lymphocytes (a type of white blood cell).
Chronic lymphocytic leukemia (also called CLL) is a blood and bone marrow disease that usually gets worse slowly. CLL is the second most common type of leukemia in adults. It often occurs during or after middle age; it rarely occurs in children.
Normally, the body makes blood stem cells (immature cells) that develop into mature blood cells over time. A blood stem cell may become a myeloid stem cell or a lymphoid stem cell.
The myeloid stem cell develops into one of three types of mature blood cells:
- Red blood cells that carry oxygen and other materials to all tissues of the body.
- White blood cells that fight infection and disease.
- Platelets that help prevent bleeding by causing blood clots to form.
The lymphoid stem cell develops into a lymphoblast cell and then into one of three types of lymphocytes (white blood cells):
- B lymphocytes that make antibodies to help fight infection.
- T lymphocytes that help B lymphocytes make antibodies to fight infection.
- Natural killer cells that attack cancer cells and viruses.
Blood cell development. A blood stem cell goes through several steps to become a red blood cell, platelet, or white blood cell.
In CLL, too many blood stem cells develop into abnormal lymphocytes and do not become healthy white blood cells. The abnormal lymphocytes may also be called leukemic cells. The lymphocytes are not able to fight infection very well. Also, as the number of lymphocytes increases in the blood and bone marrow, there is less room for healthy white blood cells, red blood cells, and platelets. This may result in infection, anemia, and easy bleeding.
This summary is about chronic lymphocytic leukemia. See the following PDQ summaries for more information about leukemia:
- Adult Acute Lymphoblastic Leukemia Treatment.
- Childhood Acute Lymphoblastic Leukemia Treatment.
- Adult Acute Myeloid Leukemia Treatment.
- Childhood Acute Myeloid Leukemia/Other Myeloid Malignancies Treatment.
- Chronic Myelogenous Leukemia Treatment.
- Hairy Cell Leukemia Treatment.
Older age can affect the risk of developing chronic lymphocytic leukemia.
Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn't mean that you will not get cancer. People who think they may be at risk should discuss this with their doctor. Risk factors for CLL include the following:
- Being middle-aged or older, male, or white.
- A family history of CLL or cancer of the lymph system.
- Having relatives who are Russian Jews or Eastern European Jews.
Possible signs of chronic lymphocytic leukemia include swollen lymph nodes and tiredness.
Usually CLL does not cause any symptoms and is found during a routine blood test. Sometimes symptoms occur that may be caused by CLL or by other conditions. A doctor should be consulted if any of the following problems occur:
- Painless swelling of the lymph nodes in the neck, underarm, stomach, or groin.
- Feeling very tired.
- Pain or fullness below the ribs.
- Fever and infection.
- Weight loss for no known reason.