Distribution of hierarchical cytogenetic abnormalities and overall survival by age among patients entered into MRC AML10 and AML11 trials (n = 2677).

In children and younger adults (younger than 55 years), normal and other intermediate groups compose the intermediate (standard) cytogenetic risk category, while those with complex karyotype (5 or more unrelated abnormalities) or adverse changes in a noncomplex karyotype compose the adverse risk group.8 In older adults (55 years or older), a revised hierarchical classification in which cases with noncomplex adverse abnormalities were reassigned to the intermediate risk category was found to be more predictive of outcome. ░ indicates favorable; ■, normal; ▤, other intermediate; ▪, noncomplex adverse; ▨, complex.