What is Chronic Lymphocytic Leukemia (CLL)?

Article written by Mohammad Omaira, MD, Bronson Oncology and Hematology Specialists

Chronic lymphocytic leukemia (CLL) is a type of cancer that starts in a crucial subset of white blood cells called lymphocytes. In CLL, abnormal lymphocytes typically build up slowly in the blood, lymph nodes and bone marrow, but can also affect other organs.

Chronic lymphocytic leukemia is the most common type of leukemia in adults, specifically in North America and Europe. It accounts for approximately 25-30% of all leukemia cases. CLL is typically found in older adults, with most diagnoses around age 70, and is rare in people under 40. Although the exact cause of CLL is not fully understood, genetic factors, family history and environmental exposures, such as pesticides, are potential risk factors.

This cancer usually grows slowly, and many people don’t show symptoms for a long time. As it progresses, it can cause swollen lymph nodes, fatigue, frequent infections, night sweats and unintentional weight loss.

Many patients with CLL don’t need immediate treatment, but should be closely monitored. Treatment options include watchful waiting for those without symptoms and various medical interventions like chemotherapy, immunotherapy or targeted therapies for more advanced cases.

Stages

CLL is classified in stages to help guide diagnosis and treatment. The most commonly used staging system is Rai classifications:

1. Complete Blood Count (CBC): Elevated lymphocyte count (lymphocytosis) is suggestive of CLL.
   
2. Flow Cytometry: Flow cytometry is essential for identifying the type of abnormal lymphocytes. It confirms that these cells are clonal B-cells by detecting specific markers like CD5, CD19, CD20 and CD23.
   
3. Bone Marrow Biopsy: A biopsy may be taken to assess bone marrow involvement, although it is not always necessary for diagnosis.
   
4. Genetic Testing: Testing can help detect genetic abnormalities that can affect how the disease progresses and guide treatment decisions.

Treatment

Managing CLL is tailored to each person and depends on the stage of the disease and whether or not there are any symptoms. Many patients in the early stages, particularly those without symptoms, may be managed with a watchful waiting and will be monitored regularly. Treatment is usually initiated when the disease becomes symptomatic or if there is evidence of rapid progression.

1. Observation: In early-stage or asymptomatic CLL, regular monitoring without immediate treatment is common. This includes periodic blood tests and physical exams to assess disease progression.
   
2. Chemotherapy: Traditional chemotherapy agents have been used to treat CLL, mostly in combination regimens. However, its use has declined as more targeted therapies have become available.
   
3. Targeted Therapies: The introduction of targeted therapies has revolutionized the treatment of CLL. These drugs specifically target cancer cells and have fewer side effects than traditional chemotherapy.
   
4. Immunotherapy: Monoclonal antibodies, such as rituximab and obinutuzumab, target specific proteins on the surface of CLL cells. These agents are often used along with chemotherapy or targeted therapies to improve efficacy.
   
5. Chimeric antigen receptor (CAR) T-cell therapy: This type of cancer immunotherapy treatment uses the patient’s own immune cells, called T cells, that are genetically altered in a lab to attack cancer cells.
   
6. Stem Cell Transplant: In younger patients or those with high-risk CLL, donor stem cell transplantation may be considered, particularly if the disease isn’t responding to other treatments. This is a more aggressive approach and carries significant risks, so it is usually reserved for specific cases.
   
7. Clinical Trials: Patients with CLL may also have the option to participate in clinical trials, which offer access to new and emerging therapies that may not yet be widely available.

The treatment options for CLL are constantly improving with new therapies providing hope for better results and longer life. Early and accurate diagnosis, along with tailored treatment plans, is crucial for managing this complex disease.

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