How is CNS disease treated in pediatric acute lymphoblastic leukemia (ALL)?

Updated: Jan 02, 2019
  • Author: Vikramjit S Kanwar, MBBS, MBA, MRCP(UK), FAAP; Chief Editor: Jennifer Reikes Willert, MD  more...
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Central nervous system (CNS) disease is divided into the following:

  • CNS 1 - Absence of blasts on cytospin preparation of cerebrospinal fluid (CSF), regardless of the number of white blood cells (WBCs)

  • CNS 2 - WBC count of less than 5/mL and blasts on cytospin findings, or WBC count of more than 5/mL but negative by Steinherz-Bleyer algorithm findings* (if traumatic tap)

  • CNS 3 - WBC count of 5/mL or more and blasts on cytospin findings and/or clinical signs of CNS leukemia, such as facial nerve palsy, brain/eye involvement, and hypothalamic syndrome (Additional intrathecal therapy is only given for CNS 3 disease.)

*If the patient has blasts in the peripheral blood and the lumbar puncture is traumatic (containing ≥5/mL WBCs and blasts), treat as CNS 3 if the CSF WBC count divided by the CSF red blood cell (RBC) count is greater than 2 times the blood WBC count divided by the blood RBC count.

CNS-2 patients are probably at increased risk for relapse. Although the Dutch Cancer and Leukemia Study group (DCLSG) demonstrated that for 526 patients on protocols ALL-7 and ALL-8, CNS-2 accounted for approximately 20% of patients and was not associated with inferior outcome. [16] More recent data from the COG Standard Risk ALL protocol suggests patients with CNS-2 had inferior outcome. Traumatic lumbar puncture at diagnosis with blasts present is also associated with poor outcome, and this has been confirmed by several study groups. For patients with ALL, the initial diagnostic lumbar puncture should be done with an adequate platelet count by an experienced pediatric oncologist.

Treatment of subclinical CNS leukemia is an essential component of acute lymphoblastic leukemia therapy. Risk factors for CNS relapse included genetic abnormality, CNS involvement at diagnosis, and T-cell immunophenotype.

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