title: Superior outcome of pediatric acute myeloid leukemia patients with orbital and CNS myeloid sarcoma: a report from the Children's Oncology Group.
abstract: BACKGROUND
  Extramedullary leukemia (EML) is common in pediatric acute myeloid leukemia (AML) and occurs as leukemia cells within the cerebrospinal fluid (CSF) or as a solid tumor (myeloid sarcoma-MS). The effect of MS on survival is unknown.
  
  
  METHODS
  Patients on CCG protocols 2861, 2891, 2941, and 2961 being treated for AML with intensive-timing chemotherapy were classified for the presence of EML (CSF leukemia, CNS-MS, orbital-MS, or non-CNS MS). CSF leukemia was classified as CNS3 (>5 WBC in the CSF with blasts) and non-CSF leukemia as CNS1/2 (<5 WBC in the CSF with or without blasts). Characteristics and outcomes of these patients were compared.
  
  
  RESULTS
  Of the 1,459 total patients, 1,206 (82%) had no EML, 154 (11%) had CSF leukemia, 19 (1%) had CNS-MS, 23 (2%) had orbital-MS, and 57 (4%) had non-CNS MS. The CR rate was significantly higher in patients with orbital-MS and CNS-MS than in those with non-MS and non-CNS MS (96% and 95% vs. 78% and 78%, P = 0.034). Patients with orbital-MS and CNS-MS had significantly higher overall survival than patients with non-CNS MS (92% and 73% vs. 38%, P < 0.001), CNS3 patients (92% and 73% vs. 51, P < 0.001), and CNS1/2 patients (92% and 73% vs. 50%, P < 0.001). Patients with orbital-MS had a significantly lower relapse rate.
  
  
  CONCLUSIONS
  Patients with MS involving orbital and CNS sites had a significantly better survival than patients with non-CNS MS, with CSF leukemia, or with no EML.
authors: Division of Hematology/Oncology, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada. djohnston@cheo.on.ca
authors: Donna L
authors: DL
authors: Johnston
authors: Todd A
authors: TA
authors: Alonzo
authors: Robert B
authors: RB
authors: Gerbing
authors: Beverly J
authors: BJ
authors: Lange
authors: William G
authors: WG
authors: Woods
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