Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) is a disorder in which the lymphocytes lose their normal ability to die and end up accumulating over time. At first, the cells increase only in the blood, but over years they also increase in the lymph nodes, liver, spleen and bone marrow.

Some patients with CLL live decades and die of infection or other diseases common in older adults.

Many patients have no symptoms at the time of diagnosis, except for an elevated white blood cell count. Some patients notice fatigue, enlargement of lymph nodes or fullness in the abdomen due to an enlarged spleen.

When CLL becomes more advanced and begins to replace normal bone marrow, low blood counts can cause:

  • Anemia, due to low levels of red blood cells
  • Infections, due to low levels of white blood cells called neutrophils
  • Bleeding, due to low levels of platelets

CLL also increases a person's risk of infection because of low production of antibodies (gamma globulins) that help fight bacteria.

In 5 percent to 10 percent of cases, CLL causes the destruction of the patient's own red blood cells and/or platelets through an "autoimmune" process. Destruction of platelets is called immune thrombocytopenic purpura (ITP), and destruction of red blood cells is called autoimmune hemolytic anemia (AHA).

Chronic lymphocytic leukemia is diagnosed through the detection of a high white blood cell count composed primarily of small lymphocytes. The diagnosis is confirmed by "immunophenotyping" (flow cytometry), which determines the types of proteins on the leukemia cells. CLL classically expresses CD19 (a B-lymphocyte protein) and CD 5 (a T-cell lymphocyte protein) simultaneously.

CLL is the one type of leukemia for which there is a formal staging system:

  • RAI Stages 0 to I — During this early stage of the disease, there is an elevated lymphocyte count (0) and enlarged lymph nodes (I).
  • RAI Stage II — In the intermediate stage the spleen becomes enlarged.
  • RAI Stages III to IV — In the advanced stage of the disease, bone marrow function is disturbed and there is a significant decrease in red blood cell (III) or platelet counts (IV).

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Most patients with early-stage chronic lymphocytic leukemia do not need any treatment when the disease is first diagnosed. These patients will live 10 to 15 years on average, and early treatment offers no advantage.

Treatment should start when the patient either has an advanced form of the disease or has an intermediate stage with significant symptoms, very enlarged lymph nodes or a rapid increase in the lymphocyte count (doubling in less than 12 months).


The most common treatment for CLL is the chemotherapy drug fludarabine. This is given intravenously (through an IV) five days a week once a month, for four to six months. Although the schedule for fludarabine is rather inconvenient, it causes only modest side effects, such as fatigue. Most patients will have a good response to this treatment and remain in remission without further treatment for two to three years.

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Reviewed by health care specialists at UCSF Medical Center.