What is the rate of increase of white blood cell (WBC) count in leukemia?

From the Guidelines

In leukemia, white blood cell counts can increase very rapidly, sometimes doubling within days or even hours in aggressive forms of the disease, with acute leukemias like Acute Myeloid Leukemia (AML) showing the fastest increases, as evidenced by the need for measures to rapidly reduce the WBC count, such as apheresis or hydroxyurea, to prevent complications like leukostasis and tumor lysis syndrome 1. The speed of increase in white blood cell count depends on the specific type of leukemia, its aggressiveness, and individual patient factors, with chronic leukemias like Chronic Myeloid Leukemia (CML) generally showing slower progression, with white cell counts increasing over months rather than days 1. Some key factors that influence the rate of increase in white blood cell count include:

• The type of leukemia, with acute leukemias being more aggressive than chronic leukemias
• The presence of certain genetic mutations, such as the FLT3 mutation in AML, which can affect the aggressiveness of the disease
• The patient's overall health and performance status, with poorer performance status and comorbid medical conditions being associated with a higher risk of complications and a faster progression of the disease 1
• The effectiveness of treatment, with prompt institution of definitive therapy being essential to prevent complications and improve outcomes 1. It is worth noting that the white blood cell count can increase rapidly in leukemia, and this can lead to symptoms like fatigue, frequent infections, easy bruising, and in severe cases, complications like tumor lysis syndrome when treatment begins, highlighting the need for close monitoring and prompt treatment 1.

From the Research

White Cell Count Increase in Leukemia

• The rate of white cell count increase in leukemia can vary depending on the type and subtype of the disease.
• In T-cell prolymphocytic leukemia (T-PLL), a distinctive hematologic aspect is a rapidly rising white blood cell count with a doubling time of weeks to months 2.
• Hyperleukocytosis, a condition characterized by a white blood cell count of greater than 100,000/µL, can occur in up to 18% of patients with acute myeloid leukemia (AML) and is associated with an adverse prognosis 3.
• The molecular processes underlying hyperleukocytosis are not fully elucidated, but interactions between leukemic blasts and endothelial cells, as well as processes in the bone marrow microenvironment, are thought to contribute to the massive entry of leukemic blasts into the peripheral blood 3.

Factors Influencing White Cell Count Increase

• The type and subtype of leukemia, such as T-PLL or AML, can influence the rate of white cell count increase.
• Genetic mutations, such as FLT3-ITD, NMP1, and CEBPA, can also impact the prognosis and management of AML 4.
• The use of intensive induction chemotherapy, allogeneic stem cell transplantation, and targeted therapies can affect the white cell count and overall outcome in patients with leukemia 5, 6.

Clinical Implications

• A rapidly rising white blood cell count can be a challenge in the diagnosis and treatment of leukemia, particularly in rare and aggressive subtypes like T-PLL 2.
• Hyperleukocytosis and leukostasis can lead to life-threatening complications, such as disseminated intravascular coagulation and tumor lysis syndrome, and require prompt and aggressive treatment 3.
• A better understanding of the underlying molecular pathophysiology of leukemia can lead to the development of novel treatments and improved patient outcomes 3, 6.