Chronic Myeloid Leukemia (CML)

Chronic myeloid leukemia (CML) is a malignant disease of the blood and bone marrow that belongs to the group of myeloproliferative disorders. CML develops when blood cell precursors in the bone marrow (primarily white blood cells) acquire a specific genetic change – the Philadelphia chromosome. This abnormality leads to the formation of the BCR-ABL gene, which causes cells to divide uncontrollably and proliferate excessively.

In many cases, CML is detected incidentally during a routine blood test. Possible symptoms include weakness, fatigue, weight loss, loss of appetite, fever, a feeling of heaviness or pain in the left upper abdomen (caused by an enlarged spleen), and recurrent infections.

Diagnostic methods for CML include:

• Complete blood count (CBC): typically shows elevated white blood cell counts and sometimes increased platelet counts.
• Peripheral blood smear: reveals white blood cells at various stages of development, along with elevated basophils and eosinophils.
• Bone marrow examination (biopsy, aspiration): confirms cellular overgrowth.
• Genetic testing (FISH, PCR): detects the Philadelphia chromosome or the BCR: ABL1 gene.

CML progresses in stages:

1. Chronic phase – the most common stage, characterized by slow disease progression and good control with medication.
2. Accelerated phase – the disease becomes more active.
3. Blast phase – the most severe stage, resembling acute leukemia.

With modern treatment, many patients remain in the chronic phase for decades. Historically, CML was associated with a significantly reduced life expectancy; however, today, thanks to tyrosine kinase inhibitors (TKIs), patient survival rates are nearly comparable to those of the general population. Many patients live for decades and may even discontinue therapy if a stable and deep molecular remission is achieved.

Main treatment approach – Tyrosine kinase inhibitors (TKIs):

• Imatinib (Glivec) – first-line therapy.
• Dasatinib, Nilotinib, Ponatinib – next-generation TKIs used in cases of resistance or intolerance to earlier drugs.

These oral medications effectively control the disease, allowing most patients to lead a normal, full life.

Other treatment options include:

• Hydroxyurea – short-term therapy, used until definitive diagnostic results are obtained.
• Interferon – an option during pregnancy, since TKIs are contraindicated.
• Bone marrow transplantation – the only potentially curative method, reserved for patients who do not respond to medical therapy.

Statistics: CML occurs most commonly in middle-aged and older adults, while it is rare in children and young people. The incidence is approximately 1–2 cases per 100,000 people per year.

Heredity: CML is not inherited; it develops as an acquired genetic change during a person’s lifetime.