Diagnostic Cerebrospinal Fluid Examination in Children With Acute Lymphoblastic Leukemia: Significance of Low Leukocyte Counts With Blasts or Traumatic Lumbar Puncture

Abstract

Purpose: To determine the significance of leukemic blasts or traumatic lumbar puncture (TLP) in diagnostic CSF of children enrolled in the Berlin-Frankfurt-Münster (BFM) Acute Lymphoblastic Leukemia–BFM-95 trial. Patients and Methods: A total of 2,021 patients were retrospectively evaluated according to initial central nervous system (CNS) status. Patients were classified as follows: CNS1 (CNS negative, n = 1,605), CNS2 (≤ 5 WBC/μL CSF with blasts, n = 103), CNS3 (CNS positive, n = 58), TLP+ (TLP with blasts, n = 135), or TLP− (TLP without blasts, n = 111). Patients with CNS2 and TLP+ status were eligible for two additional doses of intrathecal (IT) methotrexate (MTX). CNS3 patients received additional IT MTX and cranial irradiation (18 Gy). Results: CNS2, CNS3, and TLP+ groups contained a higher percentage of patients with unfavorable characteristics. Cox regression analysis identified TLP+ and CNS3 status as prognostically significant (CNS3): risk ratio (RR) = 2.3; 95% confidence interval [CI], 1.4 to 3.6; P = .0005; TLP+: RR = 1.5; 95% CI, 1.02 to 2.2; P = .04. Overall 5-year event-free survival (EFS) is 79%, for CNS1 it is 80%, and for TLP− it is 83%. CNS2 patients have an EFS of 80%, but the cumulative incidence of relapses with CNS involvement is higher compared with CNS1 patients (0.10 v 0.04). TLP+ patients have a significantly reduced EFS (73%, P = .003) because of an increased incidence of CNS relapses. CNS3 patients suffer from more systemic and CNS relapses (EFS 50%). Conclusion: CNS2 patients have the same prognosis as patients with CNS1 status, whereas the EFS of TLP+ patients is inferior to CNS1 but superior to CNS3 patients (P = .001). Both subgroups may have benefitted from additional IT MTX.