Background: Data on the impact of age in acute myeloid leukemia (AML) patients <30 years treated in pediatric and adult trials are scarce.
Methods: In all, 891 patients <18 years were treated in the pediatric trials AML-BFM 93/98 and 290 adolescents and young adults (>16 to <30 years) in the AMLCG 92/99 and AMLSG HD93/98A trials. Treatment schedules and dose intensities were comparable.
Results: Initial features and risk factors differed considerably between infants (<2 years) and older age groups and only slightly between children (2 to <13), adolescents (13 to <21) and young adults (21 to <30). Treatment results were most favorable in children (5-year event free survival [EFS]: 54% +/- 3%), slightly inferior in adolescents (46% +/- 4%, P = .03), and unfavorable in young adults (28% +/- 5%, P = .0001). Excluding patients with favorable karyotypes, the results were similar in infants and children (EFS: 44% +/- 4% and 46% +/- 3%, respectively) and inferior in adolescents (35% +/- 4%) and young adults (23% +/- 4%). There was an increased, age-related percentage and inferior outcome in patients with >5% bone marrow blasts after induction. EFS was especially poor in young adults, with blasts >5%. The blast count after induction was of no prognostic value in patients with favorable karyotypes, but a significant risk factor in patients with other cytogenetics.
Conclusions: Biologic data differed mainly between infants and older age groups. When comparing the same age groups, outcome was similar between the trial groups, which differed from reports concerning acute lymphoblastic leukemia. However, the prognosis decreased after childhood independent of other risk factors. This indicates that even in the younger cohorts increasing age may be an additional unfavorable factor.