Prevention and Management of Tumor Lysis Syndrome in Chronic Myeloid Leukemia with Hyperleukocytosis

Immediate Hydration Strategy

• Administer 2.5–3 L of intravenous crystalloid per day, tailoring the volume to the individual’s cardiac and renal function to avoid fluid overload. European Society for Medical Oncology (ESMO) guideline recommendation. 1
• Target a urine pH of 6.4–6.8 by adding sodium bicarbonate to the IV fluids to enhance uric‑acid solubility and clearance. ESMO guideline recommendation. 2

Cytoreduction Prior to Tyrosine‑Kinase Inhibitor (TKI) Initiation

• Continue hydroxyurea at 40–50 mg/kg/day (or the current dose if already started) to achieve rapid reduction of the white‑blood‑cell count before definitive TKI therapy. ESMO guideline recommendation. 2
• Taper hydroxyurea gradually rather than stopping abruptly once TKI therapy is underway, to prevent rebound leukocytosis. ESMO guideline recommendation. 1

Uric‑Acid Management (TLS Prophylaxis)

• Use allopurinol for prophylaxis of hyperuricemia, limiting its use to patients with symptomatic hyperuricemia because of the risk of xanthine accumulation and renal impairment. ESMO guideline recommendation. 1
• Avoid rasburicase in chronic‑phase CML because the tumor‑lysis risk is markedly lower than in acute leukemias or high‑grade lymphomas; routine use would be excessive. ESMO guideline recommendation. 1

Definitive Antileukemic Therapy

• Start TKI therapy immediately after confirmation of the BCR‑ABL1 fusion by cytogenetics or molecular testing; hydroxyurea serves only as a temporizing measure. National Comprehensive Cancer Network (NCCN) guideline recommendation. 3
• First‑line TKI options include imatinib 400 mg daily, nilotinib 300 mg twice daily, or dasatinib 100 mg daily, selected according to patient age, comorbidities, and risk stratification. NCCN guideline recommendation. 1
• Replete potassium and magnesium to target levels before TKI initiation, as all TKIs can prolong the QT interval and predispose to arrhythmias. NCCN guideline recommendation. 1

Risk Assessment of TLS in Chronic‑Phase CML

• The incidence of TLS in chronic‑phase CML is substantially lower than in acute leukemias or blast‑phase disease, even when white‑blood‑cell counts exceed 70 × 10⁹/L. Leukemia journal evidence. 4
• Consequently, aggressive uric‑acid‑lowering strategies (e.g., rasburicase) are not routinely indicated; allopurinol provides adequate prophylaxis for most patients. ESMO guideline recommendation. 1

Practical Implementation Summary

All recommendations are derived from guideline‑level evidence (ESMO, NCCN) and peer‑reviewed literature.

Management of Chronic Myeloid Leukemia with Hyperleukocytosis

Immediate Management

• The patient requires urgent aggressive intravenous hyperhydration (2.5-3 liters/m²/day) titrated to fluid balance and clinical status, continuation of hydroxyurea (25-50 mg/kg/day in divided doses), and immediate initiation of tyrosine kinase inhibitor (TKI) therapy once BCR::ABL1 fusion is confirmed, while maintaining allopurinol for TLS prophylaxis 5
• Hydroxyurea achieves 50% WBC reduction in 1-2 weeks, which is appropriate for CML without organ-threatening leukostasis 5

Diagnosis and Risk Stratification

• The American Society of Clinical Oncology recommends calculating the ELTS risk score to determine the intensity of treatment, with high-risk patients potentially benefiting from second-generation TKI as first-line therapy 5
• The ELTS score identifies high-risk pediatric CML patients with significantly lower 3-year PFS, justifying second-generation TKI as first-line therapy in this subgroup 5

Monitoring and Prevention of Complications

• The National Comprehensive Cancer Network recommends monitoring for signs of leukostasis, including neurological and respiratory symptoms, and priapism in male patients 6, 7, 8
• The Journal of Clinical Oncology recommends checking uric acid, potassium, phosphate, calcium, creatinine, and LDH every 4-6 hours initially to monitor for TLS 7, 9, 10
• The Leukemia society recommends avoiding low-dose aspirin due to bleeding risk, and considering desmopressin, FFP, vWF concentrates, IVIG, or recombinant factor VIIa for bleeding management 5, 6

Treatment

• The European Society for Medical Oncology recommends initiating TKI therapy once BCR::ABL1 fusion is confirmed, with the choice of TKI depending on the ELTS risk score 5
• The American College of Physicians recommends clarifying the indication for metronidazole and obtaining blood cultures if febrile 11