Leukemia is a type of cancer involving human blood cells and blood-forming tissues. There are many types of leukemia, each affecting different kinds of blood cells. 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 don’t fight infections like normal B cells do. As the number of cancerous B cells gradually increases, they crowd out normal lymphocytes and cause bone marrow failure.

CLL is the most common type of leukemia in adults. The National Cancer Institute (NCI) estimated that 20,940 new cases would occur in the United States in 2018.

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

If you do exhibit symptoms, they typically include:

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.

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

CLL is rarely diagnosed in people under the age of 40 years old. It’s typically found in people over the age of 70.

It affects more men than women. It’s also more common in Jewish people of Russian or Eastern European descent.

If your doctor suspects you have CLL, they may use various tests to confirm your 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 normal.

Immunoglobulin testing

Your doctor can use this blood test to learn if you have enough antibodies to fight infections. Find out more about immunoglobin testing.

Bone marrow biopsy

In this procedure, your doctor inserts a needle with a special tube into your hip bone or 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.

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 probably check if your lymph nodes, spleen, or liver are enlarged.

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

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 American Cancer Society (ACS).

If you have low-risk CLL, your doctor will probably 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 it 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.

To treat CLL, your doctor may recommend:

Chemotherapy

Chemotherapy is the principal treatment for CLL. It involves using medications to kill cancer cells. Depending on the exact medications prescribed, you may take them intravenously or orally.

Radiation

In this procedure, high-energy particles or waves are used to kill cancer cells. If you have painful, swollen lymph nodes, radiation therapy may help shrink them and relieve your pain.

Blood transfusions

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

Bone marrow or peripheral blood stem cell transplant

If you have high-risk CLL, 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 a new immune system.

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:

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.

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 five-year survival rate for Americans with CLL is 84.2 percent, according to the NCI. The institute also estimates that CLL will result in 4,510 deaths in the United States in 2018.

Survival rates are lower for older people with the condition. However, one study did find that up to 70 percent of Americans 75 years and older survive five years after diagnosis.

Survival rates for CLL vary widely. Your age, gender, chromosome abnormalities, and cancer cell characteristics can affect your 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.