Pediatric Acute Myeloid Leukemia and Hyperleukocytosis with WBC count
greater than 50×109/L
Abstract
Background: Acute myeloid leukemia (AML) and hyperleukocytosis are
related to an unfavorable prognosis. The impact of hyperleukocytosis on
the prognosis of pediatric AML has not been fully explained so far. We
aimed to assess the clinical characteristics and prognosis of pediatric
AML with hyperleukocytosis, referred to as white blood cell (WBC) count
≥50×109/L. Methods: A total of 307 newly diagnosed
non-acute promyelocytic leukemia patients were continuously enrolled at
our center from October 2005 to September 2015. 81 patients with initial
leukocyte counts ≥50×109/L. The baseline demographic
and clinical characteristics of AML patients were compared.
Progression-free survival (PFS) and overall survival (OS) were
documented. Results: Hyperleukocytosis occurred in 26.38% of AML
patients, and FAB M5 subtype (n=41, 50.62%) and FLT3-ITD
mutations (n=16, 19.75%) had a high proportion in AML and
hyperleukocytosis. Overall mortality was significantly higher in
patients with hyperleukocytosis than patients without hyperleukocytosis
(50.62% vs. 35.84%, P=.020). Patients with hyperleukocytosis
had a lower 10-year PFS and OS rates than those without
hyperleukocytosis (44.4%±9.4% vs. 59.7%±5.5%, P=.041;
49.4%±9.4% vs. 64.2%±5.4%, P=.051, respectively). There were
similar PFS and OS rates between the subgroups of patients with WBC
count 50-100×109/L and WBC count
≥100×109/L (43.8%±13.3% vs. 44.9%±12.3%,
P=.507; 46.9%±13.3% vs. 51.0%±12.3%, P=.907,
respectively). In all patients with hyperleukocytosis, male and FAB M5
subtype patients had a significantly inferior survival, while CBF-AML
had a better survival. Conclusions: A WBC count greater than
50×109/L at onset was a critical predictive adverse
factor in pediatric AML.