Prognostic significance of lymphocyte recovery in children with standard and high-risk precursor B acute lymphoblastic leukemia

Abstract

BackgroundThe primary aim of this study was to determine if absolute lymphocyte count (ALC) at end of induction is an independent prognostic marker of event free survival (EFS) in children with precursor B-ALL. Material & MethodsThis is a retrospective analysis of children (aged 1–18 years) diagnosed with standard and high-risk precursor B ALL. At day 29 of induction ALC (ALC29) ≥ 1.5 × 109/L was considered high and <1.5 × 109/L was considered low. ResultsTotal 260 children with (183 standard risk and 77 high risk) Precursor B ALL were included. The mean age of the study cohort was 5.2 ± 4.0 years. Fourteen patients had an event (12 relapse, 4 deaths). Mean follow-up duration was 41 months ± 20 months (median 41 months).Overall survival (OS) of the entire study cohort was 98.5% (standard risk 99.4%, high risk 96.1%, p = 0.045). EFS of the entire study cohort was 94.6% (standard risk 96.1%, high risk 90.9%, p = 0.072).ALC at any of the studied time points did not correlate with relapse. MRD at day 29 was the strongest predictor of both death (p = 0.00) and relapse (0.034). ALC29 did not differentiate EFS among MRD negative patients.However, once patients relapsed, the OS was 100% for those who had ALC>1.5 × 109/L at day 29 of initial induction chemotherapy vs 40% for those with ALC <1.5 × 109/L (p = 0.01). ConclusionWe conclude that ALC29 cannot be used to risk stratify children with pre B ALL.