Clinical and biologic features and treatment outcome of children with newly diagnosed acute myeloid leukemia and hyperleukocytosis.

BACKGROUND: Acute myeloid leukemia (AML) with hyperleukocytosis often is associated with early complications. To the authors' knowledge, no recently published study has evaluated the management and clinical course in this regard, especially in relation to pediatric patients.

METHODS: The authors reviewed 579 patients with newly diagnosed pediatric AML who were treated at St. Jude Children's Research Hospital from 1968 to 2002 and carefully examined 106 patients with initial leukocyte counts > or = 100 x 10(9)/L and French-American-British (FAB) AML subtypes other than M3. These patients with hyperleukocytosis were divided into 2 groups-'before' (early period; 70 patients) and 'after' (late period; 36 patients) the initiation of the AML-83 protocol-to address potential differences in supportive measures (including leukoreduction).

RESULTS: Forty-five patients (42.5%) had early complications that were associated strongly with M4 and M5 FAB subtypes and had higher initial leukocyte counts than the patients without complications. Early deaths were less common in the late period (2.8%) than in the early period (22.9%; P = .01), although the incidence of early complications was similar. The late period was associated with a shorter time for referral (P = .0018), a longer time from admission to chemotherapy initiation (P < .0001), and lower white blood cell counts at chemotherapy initiation (P < .0001). In the late period, patients with or without hyperleukocytosis had similar complete remission rates. However, those with hyperleukocytosis had a lower postremission 10-year event-free survival rate (21.2% vs 41.7%; P = .0228).

CONCLUSIONS: With improved management, including supportive care, early mortality in patients with AML and hyperleukocytosis decreased remarkably in the more recent period. However, better postremission treatment is required to improve long-term survival.