LOW NUMBERS OF CSF BLASTS AT DIAGNOSIS DO NOT PREDICT FOR THE DEVELOPMENT OF CNS LEUKEMIA IN CHILDREN WITH INTERMEDIATE-RISK ACUTE LYMPHOBLASTIC-LEUKEMIA - A CHILDRENS CANCER GROUP-REPORT

Purpose: This study was designed to evaluate the effect on CNS relapse (CNSR) and overall relapse rates of blast cells in the CSF containing less than or equal to 5 cells/mu L at the time of diagnosis of interm ediate-risk acute lymphoblastic leukemia (ALL) in children entered ont o ct large randomized multicenter prospective therapeutic trial (Child rens Cancer Group [CCG]-105). Patients and Methods: We studied outcome in terms of CNSR and event-free survival (EFS) in 1,544 patients who successfully completed remission-induction therapy and had been random ized to one of four systemic chemotherapy regimens and to one of two C NS prophylaxis regimens. We compared outcome between 1,450 patients wh o had varying degrees of pleocytosis but no blasts in the CSF at diagn osis (blast-negative group) with 94 who had blasts detected in the CSF after cytocentrifugation but held a total CSF WBC count of less than or equal to 5/mu L (blast-positive group). Results: No statistically s ignificant differences in overall CNSR or EFS rates were observed betw een the two groups and no differences were found when analyzed accordi ng to age or WBC count at diagnosis, sex, or type of CNS prophylaxis ( intrathecal [IT] methotrexate [MTX] alone v IT MTX plus 18 Gy cranial irradiation [CXRT]). Conclusion: In intermediate-risk ALL, there was n o significant difference in CNSR and systemic relapse rates after stan dard presymptomatic CNS therapy between patients with a CSF WBC count less than or equal to 5/mu L and those without identifiable blasts in the CSF. These findings suggest that certain approaches to therapy, su ch as that used in this study, may eliminate the need for any addition al special treatment directed at this subset of patients with CSF blas ts. (C) 1994 by American Society of Clinical Oncology.