Diagnosis of central nervous system relapse of pediatric acute lymphoblastic leukemia: Impact of routine cytological CSF analysis at the time of intrathecal chemotherapy.

Abstract

Despite the success of central nervous system (CNS) directed therapy in pediatric acute lymphoblastic leukemia (ALL), relapse involving the CNS continues to be observed in 5-10% of children when utilizing standard intrathecal prophylactic chemotherapy. While most pediatric ALL treatment protocols mandate regular lumbar punctures (LP) for the intrathecal injection of chemotherapy, the value of routine cytological analysis of cerebrospinal fluid (CSF) during therapy is unknown. Our objective was to assess the diagnostic value of routine CSF analysis during ALL therapy. To allow for at least 10 years of follow up from ALL diagnosis, children (0-18 years) with ALL diagnosed and treated at SickKids, Toronto, Canada between 1994-2004 were studied. Medical records of patients with CNS relapse were examined to determine whether CNS relapse was diagnosed based on cytology of a routinely obtained CSF sample, a CSF sample obtained because of signs and symptoms or a CSF sample obtained after the diagnosis of a bone marrow relapse. Of 494 children treated for ALL, 31 (6.6%) developed a relapse of ALL involving the CNS. Twenty-two had an isolated CNS relapse and nine had a combined bone marrow and CNS relapse. Among patients with isolated CNS relapse, 73% (16/22) were diagnosed based on routine CSF samples obtained from asymptomatic children. Conversely, 89% (8/9) of children with combined bone marrow and CNS relapse presented with symptoms and signs that prompted CSF examination. Routine CSF examination at the time of LP for intrathecal chemotherapy is useful in detecting CNS relapse.