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Prognostic significance of a low number of blasts in the cerebrospinal fluid (CSF) or a traumatic lumbar puncture (TLP) in children with acute lymphoblastic leukemia (ALL): The Dutch Pediatric Oncology Group experience.

8501 Background: The prognostic significance of a low number of blasts in the CSF (leukocytes <5/mm3) in childhood ALL is controversial. Also, it has been reported that a TLP at diagnosis has prognostic implications. Therefore, we retrospectively studied both aspects in ALL patients who were treated according to Dutch Pediatric Oncology Group protocols ALL-7/8 (1988-1996) that were identical to contemporary BFM protocols except that Dutch patients only received cranial irradiation if they had overt meningeal leukemia.


METHODS
526 evaluable patients were classified into five groups according to the following criteria: CNS1 (no blasts in the CSF, n= 304), CNS2 (blasts in the CSF, but leukocytes < 5/mm3, n=111), CNS3 (overt meningeal leukemia, n=10), TLP+ (>15/mm3 erythrocytes and blasts in the CSF, n=39), TLP- (TLP but no blasts, n=62). All CSF samples were centrally reviewed by two experienced cytologists. In addition to conventional morphology, TdT staining was done.


RESULTS
Median duration of follow up was 10.8 years, range 6.9-15.5 years. Actuarial survival percentages at 5 year were as follows: Overall event-free survival (EFS) was 72%. EFS for CNS1 patients was 74% and for CNS2 patients 71% (not significant). EFS for CNS3 patients was 67%. Probability of CSF relapse (isolated or combined) was 5.1% in CNS1 and 6.2% in CNS2 patients (N.S.). EFS in TLP- patients was 82% and in TLP+ patients 59% (p < 0.01, log rank test). Probability of CSF relapse in TLP+ patients was 9.7% and in TLP- patients 1.6% (p < 0.001). When TdT positivity was used as an additional criterion for leukemic blasts, these conclusions remained unchanged.


CONCLUSIONS
We were unable to show prognostic significance of a low number of blasts in the CSF. Our data do not support the administration of additional CNS therapy in ALL patients with a low number of CSF blasts at diagnosis. However, patients with a traumatic LP and blasts in the CSF at diagnosis have an inferior outcome and should probably receive additional treatment. No significant financial relationships to disclose.