Chronic Lymphocytic Leukemia

Epidemiology

The incidence rate of chronic lymphocytic leukemia (CLL) is 4:100,000/year in the general population, increasing dramatically with age to >30:100,000/year in individuals over 80 years 1, 2
CLL represents approximately 25% of all adult leukemias and is predominantly a disease of older adults, with a median age at diagnosis of 69-72 years and only about 10-14% of patients diagnosed before age 55 1, 3, 2

Sustained peripheral blood lymphocytosis ≥5 × 10^9/L for at least 3 months is a diagnostic criterion for CLL, with characteristic immunophenotype showing CD5+, CD19+, CD20+ (dim expression), CD23+, low surface immunoglobulin expression, and restricted kappa or lambda light chain expression 1, 4, 2, 5
Blood smear examination should show a predominance of small, morphologically mature lymphocytes 4, 6
Physical examination should include careful palpation of all lymph node areas to assess lymphadenopathy 4, 7
Flow cytometry is the most critical diagnostic test for CLL, with required markers for CLL diagnosis including CD5+, CD19+, CD20+ (dim expression), and CD23+, as recommended by the NCCN and European Society for Medical Oncology 8, 9, 1

The Binet Staging System categorizes patients into Stage A, B, or C based on hemoglobin levels, platelet counts, and involved lymphoid areas, as recommended by the European Society for Medical Oncology 10
The Binet staging system categorizes CLL into three stages:
Stage Hemoglobin Platelets Lymph Node Regions
A ≥10.0 g/dl ≥100×10⁹/l <3
B ≥10.0 g/dl ≥100×10⁹/l ≥3
C <10.0 g/dl and/or <100×10⁹/l -
The Rai Staging System categorizes patients into Stage 0, I-II, or III-IV based on lymphocytosis, lymphadenopathy, organomegaly, anemia, and thrombocytopenia, according to the European Society for Medical Oncology 10

Stage	Hemoglobin	Platelets	Lymph Node Regions
A	≥10.0 g/dl	≥100×10⁹/l	<3
B	≥10.0 g/dl	≥100×10⁹/l	≥3
C	<10.0 g/dl and/or	<100×10⁹/l	-

The Rai staging system categorizes CLL into five stages:

Stage	Characteristics
0	Lymphocytosis only
I	Lymphocytosis + lymphadenopathy
II	Lymphocytosis + hepatomegaly/splenomegaly ± lymphadenopathy
III	Lymphocytosis + anemia
IV	Lymphocytosis + thrombocytopenia

Median survival varies significantly by stage, with Binet stage A having a median survival of >10 years (63% of patients), Binet stage B having a median survival of 5-8 years (30% of patients), and Binet stage C having a median survival of 1.5-3 years (7% of patients) 3
Rai staging also predicts median survival, with Rai stage 0 (Low risk) having a median survival of >10 years (30% of patients), Rai stages I-II (Intermediate risk) having a median survival of 7 years (60% of patients), and Rai stages III-IV (High risk) having a median survival of 1.5 years (10% of patients) 3
IGHV mutation status is an important prognostic factor, with mutated IGHV associated with better prognosis and unmutated IGHV associated with worse prognosis, as described in the NCCN guidelines and European Society for Medical Oncology 8, 4
CD38 and ZAP70 expression are also prognostic factors in CLL, according to the European Society for Medical Oncology 4

The standard approach for early-stage asymptomatic disease (Binet stage A, Rai 0-II without symptoms) is "watch and wait", as recommended by the American Society of Hematology and European Society for Medical Oncology 4, 9, 6, 5
Treatment indications include significant B symptoms, progressive lymphadenopathy, splenomegaly, or hepatomegaly, progressive lymphocytosis with doubling time <6 months, cytopenias not caused by autoimmune phenomena, and Binet stage C or Rai stages III-IV 4, 9
For physically fit patients without del(17p) or TP53 mutation, treatment options include combination of fludarabine, cyclophosphamide, and rituximab (FCR) 4, 9
For elderly or less fit patients, treatment options include bendamustine + rituximab and chlorambucil + obinutuzumab 9
Targeted therapies, such as BTK inhibitors and BCL2 inhibitors, have largely replaced traditional immunochemotherapy in most treatment scenarios, according to the European Society for Medical Oncology 4
Fixed-duration therapies are gaining prominence as they are cost-effective, may avoid resistance development, and offer treatment-free intervals, as recommended by the European Society for Medical Oncology 4

Corticosteroids are first-line treatment for autoimmune hemolytic anemia (AIHA) or immune thrombocytopenia (ITP) 9
Antibiotic, antiviral, or antifungal prophylaxis is recommended for high-risk patients 9
Intravenous immunoglobulin is not routinely recommended but may be considered for patients with recurrent infections 9

For untreated patients, blood counts and clinical examinations should be performed every 3 months 4
Response evaluation should include physical examination, blood counts, and bone marrow biopsy (especially in clinical trials) 9
Bone Marrow Biopsy is not needed for initial diagnosis but is recommended before initiating therapy to evaluate unclear cytopenias, as suggested by the European Society for Medical Oncology 10 and the American Society of Clinical Oncology 4
Molecular Genetic Testing, including FISH analysis for cytogenetic abnormalities and testing for IGHV mutation status, has prognostic value, according to the American Society of Clinical Oncology 4

Avoid premature treatment of asymptomatic early-stage disease, as there is no survival benefit 4, 9
Distinguish between disease-related and autoimmune cytopenias, as management differs significantly 9
Consider comorbidities and patient fitness when selecting treatment regimens to avoid excessive toxicity 9
Be vigilant for Richter's transformation (transformation to aggressive lymphoma), which requires different management 9