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Chronic Lymphocytic Leukemia (CLL): Your Guide

Posted on May 19, 2021
Medically reviewed by
Todd Gersten, M.D.
Article written by
Maureen McNulty

Chronic lymphocytic leukemia (CLL) is a type of blood cancer that usually affects older adults. Over 21,000 people are diagnosed with CLL each year in the United States. Chronic lymphocytic leukemia makes up more than 1 out of 3 cases of leukemia in adults, making it the most common type of adult leukemia.

What Is Chronic Lymphocytic Leukemia?

CLL is a form of leukemia that affects the lymphocytes (white blood cells that help the body fight infection). CLL develops in the bone marrow — tissue found inside certain bones that produces healthy blood cells. In people with CLL, leukemia cells crowd out the normal blood cells, causing blood cell levels to drop. CLL cells may also collect in the spleen, lymph nodes, and other organs of the lymphatic system (the organ system that fights infection and removes waste).

CLL vs. SLL

Doctors consider CLL to be the same disease as small lymphocytic lymphoma (SLL). Both conditions lead to high levels of abnormal lymphocytes and are generally treated the same way. If a person’s leukemia cells are mostly found in the blood and bone marrow, they are diagnosed with CLL. If most of their cancer cells are located in the lymphatic system, they are diagnosed with SLL.

Types of CLL

There are a few different types of lymphocytes. Doctors divide CLL into subtypes depending on which type of lymphocyte is affected.

B-cell CLL, which develops from B lymphocytes, is common in 95 percent of people with CLL. This includes subtypes such as B-cell prolymphocytic leukemia (B-PLL) and hairy cell leukemia (HCL). CLL may also develop from T lymphocytes. T-cell CLL subtypes include T-cell prolymphocytic leukemia (T-PLL), large granular lymphocytic leukemia (LGLL), adult T-cell leukemia/lymphoma (ATLL), and Sezary syndrome.

Signs and Symptoms of CLL

Often, CLL does not cause symptoms until the disease becomes more advanced. Many people only discover they have CLL when routine exams or blood tests come back with unusual results. There are several possible signs and symptoms of CLL:

  • Anemia (low levels of red blood cells) can lead to fatigue, dizziness, and shortness of breath.
  • Leukopenia (low white blood cell counts) and lymphocytosis (high numbers of abnormal white blood cells) may increase the risk of infections.
  • Thrombocytopenia (low platelet counts) can cause bleeding problems and easy bruising.
  • Splenomegaly (enlarged spleen) may lead to pain or feelings of fullness in the upper left abdomen.
  • Lymphadenopathy (swollen lymph nodes) may appear as lumps in the neck, armpit, or groin.
  • Other general symptoms may include fever, chills, night sweats, weight loss, and tiredness. (This group of symptoms is sometimes referred to as B symptoms.)

Many other, more common health conditions also cause these symptoms. If you notice any symptoms that could be signs of CLL, talk to your doctor.

Read more about the signs and symptoms of CLL here.

Diagnosis of Chronic Lymphocytic Leukemia

Doctors use several tests to diagnose CLL. Diagnosis often starts with a physical exam, in which a doctor checks for any signs of disease and asks about a person’s symptoms and health history. Doctors will also usually take blood samples when diagnosing leukemia. These samples can be used for tests like a complete blood count (CBC), which measures the levels of different types of blood cells. Blood tests can also be used to determine the levels of proteins like lactate dehydrogenase (LDH) and beta-2 microglobulin. When the body has high levels of these proteins in the blood, it may be a sign of cancer.

Occasionally, doctors will use bone marrow tests to diagnose CLL. A bone marrow biopsy is used to remove a small sample of cells, and a bone marrow aspiration removes fluid from inside the bone. Bone marrow tests are not always necessary in the diagnosis of CLL.

Cells from blood or bone marrow samples may be further studied in a lab to learn more about what genes or proteins they contain. This information can help a doctor tell the difference between different types of leukemia and estimate prognosis (the outlook). Lab tests may include:

  • Immunophenotyping tests, such as flow cytometry, in which a machine “reads” the proteins found on the surface of the leukemia cells
  • Cytogenetic tests, such as fluorescence in situ hybridization (FISH) or gene mutation tests, to identify gene changes within the CLL cells
  • Serum immunoglobulin tests to show whether white blood cells are working correctly or if they are abnormal

If a person is diagnosed with CLL, they may need imaging tests to determine whether the leukemia is contained within the blood and bone marrow, or whether it has spread to other organs. Doctors may use imaging tests like X-rays, computed tomography (CT) scans, and positron emission tomography (PET) scans. Finding out where cancer cells are located in the body helps doctors determine a person’s stage of cancer.

Read more about diagnosing CLL here.

CLL Stages

Doctors use leukemia staging information to predict a person’s outlook and determine which treatments may be most helpful. There are a couple of different CLL staging systems. Doctors in the U.S. generally use the Rai system, while European doctors use the Binet system. Both of these systems are based on factors like:

  • Lymphocyte count
  • Levels of red blood cells and platelets
  • Whether a person has an enlarged liver or spleen
  • Whether a person has swollen lymph nodes

Read more about the stages of CLL here.

Treatment of CLL

Treatments can often keep CLL under control for a long time. When recommending a treatment plan, your doctor will take into account factors like your age, your overall health, your personal preferences, and what subtype and stage of CLL you have.

Watch and Wait

CLL is a slow-growing leukemia, and some people do not need to start treatment right away. People who use a “watch and wait” approach have regular follow-up visits with their doctor to monitor their leukemia. If a person begins to develop symptoms, or if tests show that CLL is getting worse, doctors may recommend starting treatment.

Medications for CLL

Treatment of chronic lymphocytic leukemia often includes multiple drugs. Chemotherapies block cancer cells from growing and dividing, which causes those cells to die. Targeted therapy medications, including monoclonal antibodies and kinase inhibitors, block specific genes or proteins that cancer cells rely on in order to survive. Targeted therapies may be less likely to cause treatment side effects.

In many cases, multiple medications are given together in different combinations to treat CLL. Some treatment options include:

  • FCR, which includes two chemotherapy drugs, Fludara (fludarabine) and Cytoxan (cyclophosphamide), and the targeted therapy drug Rituxan (rituximab)
  • PCR, which includes two chemotherapy drugs, Nipent (pentostatin) and cyclophosphamide, along with rituximab
  • The targeted therapy drugs rituximab, Imbruvica (ibrutinib), Calquence (acalabrutinib), Venclexta (venetoclax), or Gazyva (obinutuzumab), alone or in different combinations with each other
  • The steroid drug Deltasone (prednisone) along with rituximab

If CLL relapses (comes back) soon after being treated, doctors may recommend switching to different medications.

Stem Cell Transplant

People with CLL who are younger, don’t have other major health issues, and are at risk for relapse may be able to undergo allogeneic stem cell transplantation. During this procedure, a person is treated with high-dose chemotherapy. This aggressive treatment kills both leukemia cells and the bone marrow’s stem cells, which are responsible for making new blood cells. Following chemotherapy, the person receives new stem cells from a donor. Those stem cells make healthy blood cells for the person who received the transplant.

Other Treatment Options

Other procedures may be used to treat specific CLL symptoms. Doctors sometimes use radiation therapy to treat enlarged lymph nodes. Additionally, if a person with CLL has an enlarged spleen, a doctor will occasionally recommend surgically removing it. People with CLL may also be able to access new treatment options by participating in clinical trials.

Read more about treatment options for CLL.

Outlook for Chronic Lymphocytic Leukemia

In general, 85.7 percent of people with CLL will live for five years or more after being diagnosed. However, your doctor can better estimate your individual CLL prognosis by considering your own personal characteristics. Factors that may lead to a worse prognosis include:

  • Older age
  • Certain gene changes within leukemia cells
  • High levels of cells that contain the proteins ZAP-70 or CD38
  • High levels of beta-2 microglobulin in the blood
  • Quickly growing lymphocytes
  • High numbers of prolymphocytes (a type of immature white blood cell)

When estimating your outlook, your doctor may consider a system called the CLL International Prognostic Index (CLL-IPI). This system takes into account specific gene mutations, CLL stage, and age. Your doctor can use the CLL-IPI to give you a risk score that provides information about prognosis and treatment. If you have a lower risk score, you are likely to have a better outcome and may not need to use any treatment. If you are in a high-risk group, you may have a worse prognosis and your doctor may recommend more aggressive treatment.

Read more about CLL surival rate and outlook here.

Talk With Others Who Understand

MyLeukemiaTeam is the social network for people with leukemia and their loved ones. On MyLeukemiaTeam, members come together to ask questions, give advice, and share their stories with others who understand life with leukemia.

Are you living with chronic lymphocytic leukemia? Share your experiences in the comments below, or start a conversation by posting on your Activities page.

Todd Gersten, M.D. is a hematologist-oncologist at the Florida Cancer Specialists & Research Institute in Wellington, Florida. Review provided by VeriMed Healthcare Network. Learn more about him here.
Maureen McNulty studied molecular genetics and English at Ohio State University. Learn more about her here.

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