الفهرس 
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Abstract
Absolute lymphocyte count (ALC) is a simple, novel, and statistically significant indicator that has b evaluated in few studies ansubmitted as a prognostic factor in acute lymphoblastic leukemia (ALL). Objectives: To study absolute lymphocyte count at day 15 and post induction (day 42) in pediatric ALL patients, to predict its prognostic significance on outcome and to determine its role and prognostic significance in context of Minimal Residual Disease (MRD) based risk stratification. Methods: A retrospective study of 408 pediatric ALL patients who were treated at the Children’s Cancer Hospital in Egypt (CCHE) during the time period between 1st of October 2007 and end of September 2009 and followed till end of September 2010.They received ALL protocol adopted from St.Jude Children’s Research Hospital (SJCRH) study XV for low and standard / high risk. Results: A 3-year relapse free survival (RFS) and event free survival (EFS) for patients with ALC D15 with cutoff points of 350 and 1500/cmm weren’t statistically significant, while 3-year RFS for patients with ALC D42 <1500/cmm and ALC D42 ? 1500/cmm were 89.3% and 91.3% respectively which was nearly significant (p=0.056). Patients with ALC D42 ? versus <1500/cmm had a 3-year EFS of 85.6% versus 84.5% (p=0.907).ALC D42 discriminated subgroups with patients categorized by MRD D42. Patients who were MRD positive (MRD D42 ? 0.01%) and had ALC D42 <1500/cmm had 3-year RFS of 83.6% versus those with ALC D42 ? 1500/cmm who had higher 3-year RFS of 97.7% (p=0.028). Conclusion: These results suggest that ALC, a simple test, constitutes a novel prognostic factor in pediatric ALL. ALC has prognostic significance that may significantly add to MRD-based risk stratification, notably with the ability to identify a subset of MRD positive patients with a very good prognosis.