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Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL)

  • Is a type of blood cancer that begins in the bone marrow
  • Can progress either slowly or quickly depending on the form it takes

Click here to access CLL statistics.

What You Should Know

  • CLL is the most common type of leukemia in adults in Western countries. 
  • Hematologists and oncologists are specialists who treat people who have CLL or other types of blood cancer.
  • Some people have CLL that grows slowly while other people have CLL that grows faster.
  • CLL patients have a number of effective treatment options available to them.
  • For slow-growing CLL, watch and wait or watchful waiting may be an appropriate treatment approach.
  • Many people with CLL live good-quality lives for years with medical care.

What You Should Do

  • Talk with your doctor about your diagnostic tests and what the results mean.
  • Talk with your doctor about all your treatment options and the results you can expect from treatment.
  • Ask your doctor whether a clinical trial is a good treatment option for you.

To download lists of suggested questions to ask your healthcare providers, click here.

How Does CLL Develop?

The DNA (genetic material) of a developing stem cell in the bone marrow is damaged. This is called an “acquired mutation.”

  • Stem cells form blood cells (red cells, white cells and platelets).

This damaged cell becomes a leukemic cell and multiplies into many CLL cells. The CLL cells grow and survive better than normal cells.

  • CLL doesn't completely interfere with the development of mature red cells, white cells and platelets. Therefore, CLL is generally less severe than acute leukemia.

As a result, the number of healthy blood cells (red cells, white cells and platelets) is usually lower than normal.

  • Anemia is a condition when there is a low number of red cells in the blood which can cause fatigue and shortness of breath.
  • Neutropenia is a condition when there is a low number of white cells so that the immune system can't effectively guard against infection due to a lack of neutrophils (a type of white cell).
  • Thrombocytopenia is a condition when there is a low number of platelets which can cause bleeding and easy bruising with no apparent cause.
  • Low numbers of all three blood cell counts is called pancytopenia.

Two Different Forms of CLL

CLL can be slow growing and need no immediate treatment. Another form can grow at a faster rate, requiring treatment right away:

  • The slower-growing form has an increased number of lymphocytes (another type of white cell) but a normal or slightly below normal level of red cells, platelets and neutrophils in the blood. This form can remain stable for years.
  • The faster-growing form has too many CLL cells in the blood that block normal cell production. As a result, the number of fully functioning red cells and platelet levels drop lower than normal.

People with the faster-growing variety may have:

  • Enlarged lymph nodes. The nodes can compress nearby organs, causing them to function improperly. For example, an enlarged node pressing on the stomach can interfere with gastrointestinal or urinary tract functions.
  • A severe immunoglobulin deficiency. Immunoglobulins are proteins in the blood that fight infection. Low levels of immunoglobulins, sometimes combined with low neutrophil levels, can lead to recurrent infections.
  • An enlarged spleen. The spleen can press on the stomach causing early fullness (satiety) while eating food and also discomfort in the left upper part of the abdomen.

If not treated, the faster-growing form of CLL can eventually lead to anemia, neutropenia or thrombocytopenia.

Risk Factors

Doctors don't know why some cells become leukemic cells and others don't. For most people who have chronic lymphocytic leukemia (CLL), there are no obvious reasons why they developed the disease.

  • CLL has generally not been associated with any environmental or external risk factors with an exception of Agent Organge (see "A Risk for Vietnam Veterans," below).
    • Some studies also suggest that exposure to benzene in the workplace increases the risk of CLL; however, the evidence is not as strong for CLL as with other blood cancers. 
  • There are no known ways to prevent CLL.
  • You can't catch CLL from someone else.
  • Experts have found that in a small number of cases, first-degree relatives (parents and siblings) of people with CLL are approximately four times more likely to develop CLL than people who don't have first-degree relatives with the disease. However, the risk is still small. 

A Risk for Vietnam Veterans

Researchers have found a potential association between CLL and exposure to herbicides like Agent Orange used during the Vietnam conflict from 1961 to 1971. The U.S. Department of Veterans Affairs (VA) entitles those exposed to receive disability compensation. If you have CLL and think you may have been exposed to Agent Orange or other herbicides, you're entitled to benefits. The VA is urging Vietnam veterans to apply for compensation to begin processing their claims. For more information, visit the U.S. Department of Veterans Affairs website.

Source: Chronic Lymphocytic Leukemia. Reviewed by Nicole Lamanna, MD.