CLL Information
Understanding CLL

What is CLL?

Chronic lymphocytic leukemia (also called CLL) is a type of blood cancer in which the bone marrow makes too many B-lymphocytes (a type of white blood cell) that accumulate in the blood, bone marrow and lymph nodes and don’t work properly. These cells don’t fight infection as well as normal white blood cells do, they build up in the blood and stop normal blood cells like red blood cells, other white blood cell and platelets from working properly. This is what causes the symptoms that people get when they have CLL.

Although CLL is one of the most common types of leukemia in adults, with approximately 4 to 5 people in every 100,000 affected; it is considered a rare disease. It often occurs during or after middle age; it rarely occurs in children. CLL and SLL (small lymphocytic lymphoma) are considered the same disease with different presentations with SLL presenting as swollen lymph nodes with a normal lymphocyte count. CLL is classified as both a leukemia and lymphoma while SLL is classified only as a lymphoma. Both are considered forms of Non-Hodgkin’s Lymphoma (NHL).

Through one of its Steering Committee members, CLL Advocates Network´s has co-authored a “Fast Facts for Patients – Chronic Lymphocytic Leukemia” booklet published in August 2023.

To access the full booklet, click HERE.

To access the patient summary sheet, click HERE.

To order printed copies / hardcopies of the booklet, click HERE.

The primary objective of the “Fast Facts for Patients – Chronic Lymphocytic Leukemia” booklet is to empower individuals with CLL with comprehensive knowledge about their condition and treatment options.

At present, there are no known causes of CLL other than exposure to Agent Orange and possibly radiation. It is more common as people get older, in males and certain ethnic groups like Ashkenazi Jews. There is no way to prevent CLL and you cannot catch it from someone else. CLL is rarely familial.

CLL usually develops slowly and most patients enter a Watch and Wait or Active Observation stage before treatment is required. In the beginning, CLL does not cause any symptoms. Some people have CLL that progresses slowly while others have CLL that progresses quickly.

Diagnosis is made through a blood sample and it is often found during routine blood work. At time of diagnosis, one third or less of patients feel unwell and may go to their doctor with symptoms such as:

  • Fatigue
  • Swollen lymph nodes in the neck, underarm, stomach or groin
  • More frequent infections, night sweats, fevers
  • Bruising
  • Unexplained weight loss
  • Pain or fullness below the ribs due to a swollen spleen

For the other two thirds, found through routine blood work, only half will need treatment within ten years, the others may never need treatment and will continue watchful waiting or active observation.

Blood testing done at time of diagnosis may include:

  • Blood chemistry studies
  • Lactate dehydrogenase (LDH) testing
  • Beta-2-microglobulin testing
  • Flow cytometry
  • Fluorescence in situ hybridization (FISH)
  • Gene mutation testing
  • Next generation sequencing (NGS)
  • Serum immunoglobulin testing

The choice of treatment for CLL depends on your age, general health, test results and what is approved in your country for treatment. Treatment should only be started when the patient will benefit from it.

Five types of treatment are used:

  • Watchful waiting – closely monitors a patient’s condition without giving treatment until symptoms appear or change. This may be used to treat asymptomatic, symptomatic or progressive CLL.
  • Chemotherapy – uses drugs, either orally or intravenously to stop the growth of the cancer cells by killing them or to keep them from dividing. Chemotherapy is often used in combination with monoclonal antibodies (rituximab, obinutuzumab or ofatumumab). Typical chemotherapy might be FCR (fludarabine, cyclophosphamide, rituximab), BR (bendamustine, rituximab), C (chlorambucil) as well as other combinations.
  • Targeted therapy – uses drugs to block signals in the cell that cancer cell needs to grow. Examples include approved BTKIs (Bruton Tyrosine Kinase Inhibitors) such ibrutinib, idelalisib, acalabrutinib, zanabrutinib and duvelisib. BCL2 inhibitor therapy that block the B cell receptor, using venetoclax, blocks a protein on the CLL cell causing it to die. Combinations of targeted therapies that include monoclonal antibodies are also used. Monoclonal antibodies are lab made antibodies that attach themselves to the cancer cell to kill the cancer cell or block it’s growth to keep it from spreading
  • Immunotherapy –CAR T-cell is an experimental therapy that uses the patient’s own T cells that are modified in the lab to attack the blood cancer cells.
  • Radiation therapy – not commonly used but may be used on the spleen or lymph nodes if swollen and uncomfortable.

The landscape for CLL treatments is quickly changing thanks to clinical trials. For some patients, the best treatment choice maybe participation in a clinical trial


Cancer treatment and cancer can cause side effects that occur when the healthy tissues or organs are affected. Many side effects can be prevented or managed so it’s important the health care team is advised. Side effects might include:

  • Anemia (low red blood cell count)
  • Bleeding or bruising
  • Atrial fibrillation
  • Muscle and joint pains
  • Headaches
  • Liver inflammation
  • Lung inflammation
  • Constipation
  • Diarrhea
  • Fatigue
  • Loss of appetite
  • Infections and low white blood cells
  • Low platelet counts
  • Memory and concentration problems
  • Nausea and vomiting
  • Skin and nail changes

New treatments have improved the prognosis for patients with CLL. There is good data that patients looked after by a team who specialize in CLL do better. Generally, CLL progresses slowly and survival can extend for decades.

There is no evidence that anything you do as a patient will change whether your CLL progresses. It is important that you take care of your health by not smoking, get recommended vaccinations and avoid situations where you might get infections.

This information is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

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