Chronic Lymphocytic Leukemia (CLL) is a type of cancer that affects B-lymphocytes, a type of white blood cell. These abnormal cells originate in the bone marrow and accumulate in the blood, lymph nodes, and spleen. Blood tests are fundamental for diagnosing CLL, understanding its characteristics, and managing the disease over time.
Core Diagnostic Blood Tests
When CLL is first suspected, a complete blood count (CBC) is typically performed. This test measures blood components, including white blood cells, red blood cells, and platelets. In CLL, a CBC often reveals an elevated white blood cell count, primarily due to increased lymphocytes (lymphocytosis). In advanced stages, the CBC may also indicate low red blood cells (anemia) or low platelets (thrombocytopenia).
Following an abnormal CBC, flow cytometry confirms the diagnosis. Flow cytometry analyzes surface markers (proteins) on lymphocytes in the blood. CLL cells display a unique pattern of these markers, including CD5, CD19, CD20 (dim), and CD23. This specific marker combination definitively identifies cancerous B-cells and confirms CLL.
Advanced Tests for Understanding CLL
After diagnosis, additional blood tests characterize CLL cells, influencing disease progression and treatment. Fluorescence In Situ Hybridization (FISH) examines chromosomes in CLL cells for abnormalities. Common changes include deletions on chromosomes 13q, 11q, and 17p, and trisomy 12. The presence of del(17p) is significant, associated with more aggressive CLL and impacting treatment effectiveness.
Immunoglobulin Heavy Chain Variable Region (IGHV) mutation status analysis evaluates antibody-producing genes in CLL cells. This test classifies CLL into “mutated” or “unmutated” IGHV. Patients with mutated IGHV typically have slower disease progression, while unmutated IGHV often indicates a more aggressive form requiring earlier or more intensive treatment.
TP53 mutation analysis looks for changes in the TP53 gene, a tumor suppressor. A mutation in the TP53 gene can indicate a more aggressive disease course and may influence therapeutic agent selection. Beta-2 microglobulin is a non-specific blood marker that can be elevated in CLL. While not diagnostic, its levels can sometimes correlate with disease burden and provide insights into prognosis.
Blood Tests for Ongoing Monitoring
Blood tests are integral for managing CLL, especially for patients on “watch and wait” or active treatment. Regular CBCs track changes in lymphocyte, red blood cell, and platelet levels. This monitoring assesses disease progression, identifies complications like worsening anemia or thrombocytopenia, and gauges treatment impact.
During CLL treatment, blood tests (primarily CBCs and sometimes flow cytometry) assess therapy effectiveness. These tests track CLL cell reduction and blood count improvement, indicating treatment efficacy. Blood tests also detect treatment side effects or complications, like infections, by monitoring white blood cells.
Organ function tests (kidney and liver health) may also be conducted to ensure these organs are not adversely affected by disease or treatment. If the disease progresses or treatment strategy changes, advanced tests like FISH or TP53 mutation analysis may be repeated. This provides updated genetic information to inform subsequent therapeutic decisions.