OBJECTIVETo evaluate the outcomes of childhood acute monocytic leukemia (AML-M5) and explore the indications of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for children with AML-M5.

METHODSeventy-five AML-M5 patients and 201 non-AML-M5 AML patients were enrolled in this retrospective analysis. Event-free survival (EFS) and overall survival (OS) rates were estimated by Kaplan-Meier method and prognostic factors were evaluated by COX regression with SPSS.

RESULT(1) Twelve patients gave up treatment after confirmed diagnosis. Two patients died on the second day after chemotherapy. Of the 61 patients, 73.8% (45/61) achieved complete remission (CR) after two courses of chemotherapy. The 5-year EFS rate was 34.5% ± 6.8%. But of the 117 non-AML-M5/M3 AML patients, the 5-year EFS rate was 51.0% ± 4.9%. (2) Multivariate analysis showed that age ≥ 10 y, the proportion of bone marrow blast cell counts ≥ 15% after the first induction therapy, not CR after two courses of chemotherapy were risk factors for the long-term prognosis. (3) Of the 20 patients whose bone marrow blast cell counts ≥ 15% after the first induction therapy, 5 patients who choose allo-HSCT had a better OS than the other 15 patients who choose chemotherapy only (60.0% ± 21.9% vs. 7.3% ± 7.1%, P = 0.024).

CONCLUSIONChildren with AML-M5 had a poorer prognosis than the other AML patients; patients whose bone marrow blast cell counts ≥ 15% after the first induction therapy chose allo-HSCT had a better prognosis. At present, there is no enough evidence to support that patients whose bone marrow blast cell counts < 15% after the first induction therapy should choose unrelated donor for allo-HSCT.