Blasts in CSF with a normal cell count do not justify alteration of therapy for acute lymphoblastic leukemia in remission: a Childrens Cancer Group study.

Abstract

The Childrens Cancer Group (CCG) requires both a CSF WBC count of more than five cells per microliter and demonstration of blast cells in the cytocentrifuge specimen to support a diagnosis of CNS relapse. We reviewed the CSF examinations of patients with intermediate-risk acute lymphoblastic leukemia (ALL) to determine the clinical significance of blast cells reported in the cytocentrifuge when the total CSF cell count was normal. Children treated on CCG-105 for ALL had CSF examinations every 12 weeks during maintenance therapy. The outcome of children who had a positive CSF cytocentrifuge examination without an elevated CSF WBC count was compared with that of children who did not have any CSF blast cells observed. Sixty-four patients had 81 CSF examinations with blast cells and a normal cell count. By Cox life-table regression analysis, patients with blasts had a different disease-free survival (DFS) distribution, with relapses tending to occur earlier (P = .008). However, the DFS for these patients was 63% +/- 9.6% at 5 years from the time of the abnormal cytocentrifuge result as compared with 69% +/- 1.5% for 1,490 children who did not have blasts in their CSF. This difference is not significant. Blast cells were infrequently identified in cytocentrifuge preparations of CSF when the cell count was normal. The majority of patients in whom such an event was observed have not experienced a subsequent relapse as measured by life-table analysis at 5 years. The data do not justify changing or augmenting therapy based on cytocentrifuge results alone.