Prognostic Variables in Newly Diagnosed Children with Acute Myeloid Leukemia: AML-XH-99.

In children with acute myeloid leukemia (AML), very few factors recognizable at diagnosis or shortly appear to affect outcome, especially in resource-poor countries. Recently, as therapy has gradually improved, a number of factors have begun to emerge as consistently significant in predicting outcome. The objective of this study was to assess prognostic value of biologic presenting features and therapy-associated parameters as well as risk classification of AML-XH-99 in childhood acute myeloid leukemia (AML). Among the children with AML who entered protocol of AML-XH-99 from January 1998 to May 2003, 75 patients with newly diagnosed AML comprise the basis for this report. Biologic presenting features (gender, age, white blood cells, platelet counts, French-American-British category, cytogenetic abnormalities) and therapy-associated factors (blast cell counts in the bone marrow at hours 48 after the first induction course, complete remission rate after the first course of induction therapy) were analyzed. Probability of event-free survival (pEFS) was estimated by Kaplan-Meier analysis and the distributions of pEFS were compared using the log-rank test. Chi-square analysis or Fisher exact test were used to compare the differences in the distribution of biologic presenting features and therapy-associated factors. A Cox proportional hazards model was used to identify independent prognostic factors. Univariate comparisons of the proportion of patients attaining complete remission after induction indicate that French-American-British category M5, blasts≥ 0.15 in the bone marrow at hour 48 after the first induction course and patients who did not achieve a complete remission after the first induction course were associated with lower complete remission rates (P=1.28E-03, 0.011, 3.31E-04 respectively). Univariate analysis demonstrated that the probability of 5-year event-free survival (EFS) for patients with age (<1-year or >10-year), platelet count(<20×10⁹/L), French-American-British category M5, hepatomegaly, blasts≥ 0.15 in the bone marrow at hour 48 after the first induction course and patients who did not achieve a complete remission after the first induction course, central nervous system leukemia was unfavorable [The probability of 5-year pEFS was 0.00% or 46.53±12.59%, 28.29±10.75%, 30.77±14.26% (The probability of 28-month EFS with M5), 39.46±10.47%, 18.18±15.12%, 14.74±11.60%, 0.00%, respectively], while the outcome of patients with cytogenetic abnormalities of t (8; 21), t (15; 17) was better (The probability of 5-year EFS was 46.97±13.13%, 90.00±9.49%, respectively). Multivariate analysis suggests cytogenetic abnormality of t (15; 17), having achieved a complete remission after the first induction course as well as without central nervous system leukemia were independent prognostic factors(hazard ratio, 5.167, 7.376, 5.551, respectively; P=0.023, 0.007, 0.018, respectively). This report suggested combining the cytogenetic abnormalities with early treatment response has important prognostic significance, and can be predicted outcome even in patients achieving a complete remission.