Epidemiology of Chronic Leukemias
Key Point
Chronic myeloid leukemia (CML) is the most common chronic leukemia in adults, accounting for 15–20% of all leukemias in developed countries and up to 25% in India.
Diagnostic Features of CML
| Feature | CML |
|---|
| Cytogenetic hallmark | t(9;22) Philadelphia chromosome (BCR-ABL fusion) |
| Median age at diagnosis | 50–60 years |
| Splenomegaly | Present in 50% of cases |
| WBC count | Often markedly elevated (>100,000/μL) |
| Bone marrow | Hypercellular with myeloid predominance |
| Prognosis (pre-TKI era) | Median survival ~3–5 years |
Chronic Leukemia Frequency Ranking
- 1.
Chronic myeloid leukemia — 40–50% of chronic leukemias
- 2.
Chronic lymphocytic leukemia — 30–40% of chronic leukemias (more common in Western populations)
- 3.
Chronic neutrophilic leukemia — <5% of chronic leukemias
- 4.
Chronic eosinophilic leukemia — Rare, often associated with FIP1L1-PDGFRA
High-YieldNEET PG
The presence of t(9;22) (Philadelphia chromosome) is pathognomonic for CML and is present in >95% of cases. The BCR-ABL fusion protein has constitutive tyrosine kinase activity, driving uncontrolled myeloid proliferation.
Clinical Pearl
In India, CML represents a significant proportion of hematologic malignancies due to delayed diagnosis and presentation in advanced disease stages. Early recognition via cytogenetics or BCR-ABL PCR is critical for initiating tyrosine kinase inhibitor (TKI) therapy.
Mnemonic: CML = Common Myeloid Leukemia — remember it as the most frequent chronic leukemia in adults globally.
