OBJECTIVETo analyze the relationship between karyotypic characteristics and treatment outcome of childhood acute lymphoblastic leukemia (ALL) and compare the difference in karyotypic aberration between ALL patients in China and in western countries.

METHODSFrom January 1998 to May 2003, 193 patients with newly diagnosed ALL were enrolled on protocol ALL-XH-99. The patients were classified into 4 groups according to the karyotype of the leukemia cells: normal karyotype, hypodiploid, hyperdiploid and pseudodiploid. Event-free survival (EFS) was estimated by Kaplan-Meier analysis and the distributions of EFS were compared using the log-rank test. A Cox proportional hazards model was used to identify independent prognostic factors.

RESULTS(1) Of 193 ALL patients, 115 had cytogenetic data. There were 53 (46.09%) with normal karyotype, 29 (25.22%) hyperdiploid, 9 (7.83%) hypodiploid, 4 coexpression of hypodiploid/hyperdiploid and 20 (17.39%) pseudodiploid. The probability of 5-year EFS for the four subgroups were (78.28 +/- 6.34)%, (86.07 +/- 6.47)%, (53.85 +/- 13.83)% and (40.10 +/- 12.17)%, respectively (P = 0.0041). (2) The clinical presentation and early response to treatment had no difference among the four groups, but the events are significantly different. (3) The probability of 5-year EFS for the combined hypodiploid group and the non-hypodiploid group was (53.85 +/- 13.83)% and (69.98 +/- 5.94)%, respectively (P = 0.1281). (4) The probability of 4-year EFS was significantly worse for patients with Philadelphia chromosome than for no Philadelphia chromosome patients [(28.57 +/- 17.07)% vs (70.85 +/- 5.60)%, P = 0.0009]. (5) Multivariate analysis suggested that the karyotypic characteristics, Philadelphia chromosome, age < 1-year or > 12-year, and white blood cell counts were independent prognostic factors.

CONCLUSIONSThe cytogenetic pattern of Chinese childhood ALL patients was similar to that of western countries. Cytogenetic findings especially Philadelphia chromosome had important prognostic significance.