Cumulative incidence of relapse in children with ALL, according to levels of residual disease (RD) on flow cytometric assessment on day 19 of remission-induction therapy.

Levels of RD were defined by the percentage of mononuclear cells expressing leukemia-specific immunophenotypes. (A) Patients with an RD level of 0.01% or more (solid line) compared with patients with an RD level below 0.01% (broken line). (B) Cumulative incidence of relapse in patients with different levels of detectable RD.