What Is Chronic Lymphocytic Leukemia?

Health Writer

Chronic lymphocytic leukemia (CLL) is a slowly developing cancer that affects the white blood cells in the bone marrow. White blood cells, called lymphocytes, help your body fight infection. When you have CLL, the lymphocytes do not mature properly. They also do not die as quickly as other cells, causing the normal cells to be crowded out. CLL can spread from the bone marrow to the blood and to other parts of the body, including the liver, lymph nodes and spleen. CLL is the most common type of leukemia in adults.

Types of CLL

There are two types of CLL. One grows very slowly and may not require immediate treatment. You might have this type of CLL for many years and never have any symptoms.

The second type of CLL is more serious and grows much faster. You may have enlarged lymph nodes, low levels of infection-fighting immunoglobins in your blood, and an enlarged spleen.

Although the cells from both types look similar, a laboratory test can determine which type you have.


When you have CLL, it can take years for the leukemic cells to grow and build up in the bone marrow and spread to other areas of the body. Many people go for a long time without any symptoms. They may not know they have leukemia until they have a routine blood test or are being examined for an unrelated health problem.

Symptoms that do show up may be vague and common to all sorts of ailments. These include:

  • Weakness
  • Fatigue
  • Weight loss
  • Chills
  • Fever
  • Night sweats
  • Swollen lymph glands
  • Sense of fullness in the abdomen

As the cancer progresses, there may be complications, such as:

Anemia – When the leukemic cells crowd out other blood cells, it can cause anemia, in which you don’t have enough red blood cells to bring enough oxygen to the tissues in your body, making you feel tired and short of breath.

Frequent infections – CLL affects the white blood cells that help you fight infections and causes your immune system to not work properly. You may have frequent infections or feel as if an infection doesn’t get better.

Excessive bruising or bleeding – CLL can crowd out your blood platelets, which can lead to frequent bruising, nosebleeds, or bleeding gums. You may notice excessive bleeding after an injury.

Causes and risk factors

We don’t know the exact cause of CLL. Some families may have more than one person with CLL; however, it is not considered hereditary. There may be some people who are more susceptible to developing CLL. These risk factors include:

  • Age - Being over 45 years old
  • Gender - Being male
  • Ethnicity - Being white, especially those with Russian Jewish or Eastern European Jewish ethnicity
  • Family - Having other family members with CLL or with cancers of the lymph system (such as lymphoma)

You may also have an increased risk if you were exposed to Agent Orange during the Vietnam War. Otherwise, CLL has few known risk factors that you can control, so there is no way to prevent it.


There are five standard treatments used to treat CLL:

Watchful waiting - This may be used if you have the slow growing CLL. You won’t receive treatment until symptoms appear or the cancer begins to change.

Radiation therapy - This uses the same type of radiation as with x-rays but at much higher doses to kill the cancer cells or prevent them from reproducing.

Chemotherapy - This is a drug, or combination of drugs, used to kill the cancer cells.

Surgery - If you have an enlarged spleen, you may need to have a splenectomy to have the spleen removed.

Targeted therapy - This is a type of therapy that uses drugs or other substances to target and kill the cancer cells without harming the normal cells.

There are also a number of different treatments currently being researched in clinical trials:

You can search for clinical trials at the National Cancer Institute, the Leukemia & Lymphoma Society or CenterWatch.


CLL is usually not curable, but most people with the slow-growing form of the disease live for many years. Many people are treated on and off; the treatment stops during times of remission, and then when the cancer returns, the treatment is started again. This may continue throughout your life.

Because CLL can severely impact your immune system, it is important to talk to your doctor about vaccines and other preventive measures you can take to avoid infections that can make you seriously ill, such as the flu or pneumonia.

See more helpful articles:

How Leukemia Is Diagnosed in Adults

Living Past Leukemia: Survivorship and Lasting Side Effects

Leukemia: A Gene-Related Disease, But Usually Not Hereditary