Chronic lymphocytic leukemia (CLL) is a slow-progressing blood and bone marrow cancer. It causes blood stem cells to produce too many white blood cells, and this may limit the development of other healthy blood cells.

CLL is the most common form of leukemia in adults over 20 years of age. While it primarily affects the bone marrow, the cancerous cells can reach the bloodstream and spread to other areas, such as the lymph nodes, spleen, and liver.

This article discusses the different types of CLL, their symptoms, how doctors may diagnose and treat the disease, and a person’s outlook.

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There are two classifications of CLL — indolent and aggressive. Indolent CLL is stable, slow growing, or low grade. Aggressive CLL grows quickly.

Indolent CLL

For a person with indolent CLL, the blood has higher than usual levels of lymphocytes, or B cells, a form of white blood cell. The numbers of red blood cells, platelets, and neutrophils are normal or slightly low.

People with indolent CLL may have no symptoms, and doctors may only discover the disease while performing routine tests for other conditions.

Indolent CLL may not require treatment. Doctors may recommend waiting to see whether any symptoms or signs of the cancer progressing develop.

Aggressive CLL

Aggressive CLL causes an overproduction of cancerous cells, and this limits the production of healthy blood cells. As a result, the number of red blood cells, platelets, and neutrophils is likely to be low.

People with aggressive CLL may have:

  • Enlarged lymph nodes: These can press into organs, such as the stomach, and in this case can interfere with gastrointestinal function.
  • Immunoglobulin deficiency: This can make a person more susceptible to contracting infections.
  • Enlarged spleen: This can make a person feel full after only eating small amounts and can cause discomfort and pain in the upper-left abdomen.

A person with CLL may have no symptoms. Doctors usually discover this cancer through routine blood tests.

People who do have symptoms may develop them gradually. They are generally mild at first and may worsen over months and years as the cancerous cells build up in the body.

Signs and symptoms of CLL can include:

As CLL progresses, the cancerous cells replace the blood-making cells in bone marrow.

This can lead to anemia, a shortage of red blood cells, and thrombocytopenia, a shortage of blood platelets. Thrombocytopenia can result in bruising, nosebleeds, and bleeding gums.

A doctor diagnoses CLL based on the appearance of abnormal cells under a microscope. To do this, the doctor requests blood exams, such as a complete blood count.

Doctors also check for characteristic molecular and cellular markers on the surfaces of these cells. They do so with a technique called flow cytometry.

Other tests that a doctor may conduct include:

  • Bone marrow tests: While these are not strictly necessary for diagnosing CLL, they can help rule out any other conditions. These tests can also help show how well CLL treatment is working.
  • A quantitative immunoglobulin test: This checks how many antibodies are present in the blood. CLL prevents the body from making antibodies.
  • Fluorescence in situ hybridization (FISH): A FISH test uses a DNA probe to check for abnormalities in cells. A doctor may use this to assess whether the person needs treatment and to determine the best approach.
  • Karyotyping: This test looks at the chromosomes in a blood or bone marrow sample to check for any abnormalities in their size, shape, or number.
  • DNA sequencing: This test looks at the DNA in blood or bone marrow samples to check for abnormalities. A doctor may use this to help estimate a person’s prognosis.
  • A beta-2 microglobulin test: CLL cells can produce beta-2 microglubulin proteins, and this can make the cancer harder to treat. This test looks for these proteins.

If CLL is indolent, the doctor may recommend watchful waiting. Instead, if the cancer is aggressive and progressing, they begin treatment.

The following can be signs that CLL is progressing:

  • recurrent infections
  • a fever of over 100.5ºF for at least 2 weeks
  • night sweats for at least 1 month, without an infection
  • unintentional weight loss over 6 months
  • extreme fatigue
  • a loss of appetite
  • autoimmune hemolytic anemia or autoimmune thrombocytopenia that does not respond to corticosteroids
  • progressive bone marrow failure

The doctor may recommend the following treatments:

  • Chemotherapy: This involves taking specific medication to kill the cancerous cells. People often have several courses of chemotherapy with rest periods between.
  • Targeted therapy: These oral drugs target specific cells, and the best choice of drug can depend on a person’s age and how far their CLL has progressed.
  • Radiation therapy: This is a rare approach to CLL, but it can help reduce an enlarged spleen or large lymph nodes that are interfering with organ function. It may also help treat pain that stems from the bone marrow.
  • Splenectomy: For some people with CLL, cancer cells gather in the spleen. If a person also has an autoimmune condition, their doctor may recommend this procedure to remove the spleen.

For a person with CLL, the survival rate ranges from 2–20 years, with an average of 10 years. This means that on average, people with CLL live at least another 10 years after a doctor diagnoses the condition.

A person with indolent CLL has a survival rate of up to 20 years with no treatment.

It is worth keeping in mind that all survival rates are based on averages of past data, and they may not take into account recent advances in detection and treatment. Also, factors specific to each person may play an important role. A doctor can provide specific information.

If a person has no symptoms, their doctor will recommend regular testing every 3–12 months to check whether the cancer is progressing. People with CLL are also up to seven times more likely to develop secondary cancer, including acute myeloblastic leukemia.

Learn more about the survival rates for people with CLL.

Indolent CLL is a slow-growing cancer of the blood and blood marrow. It may cause no symptoms. A doctor will monitor it closely and may only recommend treatment if it shows signs of progressing.

The best approach to treatment will depend on how far the cancer has progressed and the symptoms it causes, among other factors specific to each person.