Leukemia is a type of cancer involving human blood cells and blood-forming cells. Typically, leukemia is a cancer of the white blood cells, but different types of leukemia can start in other blood cell types. The types of leukemia are based on whether the condition is acute (fast-growing) or chronic (slower-growing).

Chronic lymphocytic leukemia, or CLL, affects lymphocytes.

Lymphocytes are a type of white blood cell (WBC). CLL affects B lymphocytes, which are also called B cells.

Normal B cells circulate in your blood and help your body fight infection. Cancerous B cells do not fight infections as normal B cells do. As the number of cancerous B cells gradually increases, they crowd out normal lymphocytes.

CLL is a common type of leukemia in adults. The National Cancer Institute (NCI) estimates that there were about 20,160 new cases in the United States in 2022.

Some people with CLL may not have any symptoms, and their cancer may only be discovered during a routine blood test.

If you do have symptoms, they typically include:

  • fatigue
  • fever
  • frequent infections or illness
  • unexplained or unintended weight loss
  • night sweats
  • chills
  • swollen lymph nodes

During a physical examination, your doctor may also find that your spleen, liver, or lymph nodes are enlarged. These can be signs that cancer has spread to these organs. This often happens in advanced cases of CLL.

If this happens to you, you may feel painful lumps in your neck or a sensation of fullness or swelling in your belly.

If your doctor suspects you have CLL, they may use various tests to confirm the diagnosis. For example, they’ll probably order one or more of the following tests.

Complete blood count (CBC) with white blood cell (WBC) differential

Your doctor can use this blood test to measure the number of different types of cells in your blood, including different types of WBCs.

If you have CLL, you’ll have more lymphocytes than you typically should have.

Immunoglobulin testing

Your doctor can use this blood test to learn if you have enough antibodies to mount an immune response against infections.

Bone marrow biopsy

In this procedure, your doctor inserts a needle with a special tube into your hip bone, pelvic bone, or occasionally the breastbone to get a sample of your bone marrow for testing.

CT scan

Your doctor can use the pictures created by a CT scan to look for swollen lymph nodes in your chest or abdomen.

Flow cytometry and cytochemistry

With these tests, chemicals or dyes are used to see distinctive markers on the cancer cells to help determine the type of leukemia. A blood sample is all that’s needed for these tests.

Genomic and molecular testing

These tests look at the genes, proteins, and chromosome changes that may be unique to certain types of leukemia. They also help determine how quickly the disease will progress and help your doctor choose which treatment options to use.

The genetic testing to find such changes or mutations could include fluorescence in situ hybridization (FISH) assays and polymerase chain reaction.

Experts don’t exactly know what causes CLL. However, there are risk factors that increase a person’s likelihood of developing CLL.

Here are some risk factors that have the potential to raise a person’s likelihood of developing CLL, according to the American Cancer Society (ACS):

  • Age. CLL is rarely diagnosed in people under 40 years old. The majority of CLL cases are diagnosed in people over age 50.
  • Sex. It affects more men than women.
  • Monoclonal B-cell lymphocytosis. There’s a small risk that this condition, which causes higher than normal levels of lymphocytes, can turn into CLL.
  • Environment. The U.S. Department of Veterans Affairs included exposure to Agent Orange, a chemical weapon used during the Vietnam War, as a risk factor for CLL.
  • Family history. People who have immediate relatives with a CLL diagnosis have a higher risk for developing CLL.

According to the ACS, CLL is more prevalent in North America and Europe than Asia.

If you have low risk CLL, your doctor may advise you to simply wait and watch for new symptoms. Your disease may not worsen or require treatment for years. Some people never require treatment.

In some cases of low risk CLL, your doctor may recommend treatment. For example, they may recommend treatment if you have:

  • persistent, recurrent infections
  • low blood cell counts
  • fatigue or night sweats
  • painful lymph nodes

If you have intermediate or high risk CLL, your doctor will probably advise you to proceed with treatment right away.

Below are some treatments your doctor may recommend.


Depending on certain factors such as age, the extent of symptoms, and overall health, chemotherapy may be recommended for some individuals living with CLL. Chemotherapy involves using medications to kill cancer cells. Depending on the exact medications your doctor prescribes, you may take them intravenously or orally.

Targeted therapies

Targeted therapies focus on the specific genes, proteins, or tissues that contribute to the cancer cells’ survival. These could include:

  • radiation therapy, which uses high-energy particles or waves to kill cancer cells
  • monoclonal antibodies, which attach to proteins
  • kinase inhibitors that can destroy cancer cells by blocking certain kinase enzymes

Bone marrow or peripheral blood stem cell transplant

If you have high risk CLL, and meet the age and overall health requirements, this treatment may be an option. It involves taking stem cells from the bone marrow or blood of a donor — usually a family member — and transplanting them into your body to help establish healthy bone marrow.

Blood transfusions

If your blood cell counts are low, you may need to receive blood transfusions through an intravenous (IV) line into a vein to increase them.


In some cases, your doctor may recommend surgery to remove the spleen if it’s become enlarged due to CLL.

Chemotherapy weakens your immune system, leaving you more vulnerable to infections. You may also develop abnormal levels of antibodies and low blood cell counts during chemotherapy.

Other common side effects of chemotherapy include:

  • fatigue
  • hair loss
  • mouth sores
  • loss of appetite
  • nausea and vomiting

In some cases, chemotherapy can contribute to the development of other cancers.

Radiation, blood transfusions, and bone marrow or peripheral blood stem cell transplants can also involve side effects.

To address specific side effects, your doctor may prescribe:

  • anti-nausea medications
  • blood transfusions
  • prophylactic antibiotics or antivirals
  • IV immunoglobulin
  • corticosteroids
  • the medication rituximab

Talk with your doctor about the expected side effects of your treatment. They can tell you which symptoms and side effects require medical attention.

The 5-year survival rate for Americans with CLL is about 87.2 percent, according to the NCI.

According to a 2021 analysis, survival rates can be lower for older individuals with the condition, but even those survival trends are increasing because of new therapies and treatments that are available.

If your doctor determines that you have CLL, they will order further testing to gauge the extent of the disease. This helps your doctor classify the stage of the cancer, which will guide your treatment plan.

To stage your CLL, your doctor will probably order blood tests to obtain your red blood cell (RBC) count and specific blood lymphocyte count. They’ll also likely check whether your lymph nodes, spleen, or liver are enlarged.

Under the Rai system of classification, CLL is staged from 0 to 4. Rai stage 0 means CLL is the least severe, while Rai stage 4 is the most advanced.

For treatment purposes, the stages are also grouped into levels of risk. Rai stage 0 is low risk, Rai stages 1 and 2 are intermediate risk, and Rai stages 3 and 4 are high risk, explains the ACS.

Here are some typical CLL symptoms at each stage:

  • Stage 0: high levels of lymphocytes
  • Stage 1: high levels of lymphocytes; enlarged lymph nodes
  • Stage 2: high levels of lymphocytes; lymph nodes may be enlarged; enlarged spleen; potentially enlarged liver
  • stage 3: high levels of lymphocytes; anemia; lymph nodes, spleen, or liver may be enlarged
  • stage 4: high levels of lymphocytes; lymph nodes, spleen, or liver may be enlarged; possible anemia; low levels of platelets

Overall, survival rates for CLL are on the higher side, but these rates can vary. Your age, sex, chromosome abnormalities, and cancer cell characteristics can all affect your long-term outlook. The disease is rarely cured, but most people live for many years with CLL.

Ask your doctor about your specific case. They can help you understand how far your cancer has progressed. They can also discuss your treatment options and long-term outlook.