Risk factors and therapy for isolated central nervous system relapse of pediatric acute myeloid leukemia.

PURPOSE: CNS relapse of pediatric acute myeloid leukemia (AML) is an infrequent occurrence. This review examines the risk factors and therapy used for patients with an isolated CNS relapse. PATIENTS AND METHODS: Records of 886 patients with de novo AML were reviewed, and patients who entered remission at the end of one course of therapy and developed an isolated CNS relapse as their first event were analyzed (n = 690).
RESULTS: Thirty-three patients developed an isolated CNS relapse. Factors at diagnosis significantly associated with an isolated CNS relapse, compared with no CNS relapse, included age 0 to 2 years (70% v 27%, respectively; P < .001), enlarged liver (79% v 39%, respectively; P < .001) or spleen (79% v 39%, respectively; P < .001) at diagnosis, CNS disease at diagnosis (33% v 9%, respectively; P < .001), median WBC count (79.2 v 19.3 x 10(3) microL, respectively; P < .001), French-American-British M5 morphology (45% v 15%, respectively; P < .001), and chromosome 11 abnormalities (44% v 18%, respectively; P = .022). Treatment of the isolated CNS relapse varied from local therapy with intrathecal chemotherapy and/or radiation therapy to systemic therapy with chemotherapy with or without bone marrow transplantation. Survival rate in the patients treated with local therapy was only 31.5% compared with 21.4% in patients treated with systemic therapy. The 8-year overall survival for patients after an isolated CNS relapse was similar to patients after a bone marrow relapse (26% +/- 16% v 21% +/- 5%, respectively).
CONCLUSION: Significant predictors for isolated CNS relapse were identified. This study demonstrated that there may be no benefit to systemic therapy versus CNS-directed therapy in outcome. The data support CNS-directed therapy to treat isolated CNS relapse.