Prognostic factors in childhood acute lymphoblastic leukemia in Japan

A retrospective analysis of children with acute lymphoblastic leukemia (ALL ) was performed to evaluate the current status of diagnosis and treatment o f ALL in Japanese children. Clinical records of 670 children with ALL were collected and analyzed; these children had been diagnosed between 1991 and 1995 at the 53 institutions in 4 areas participating in the Japan Associati on of Childhood Leukemia Study. It was found that T-cell ALL was significan tly less frequent in Tokai and Hokkaido than in Kansai and Chu-Shikoku. The overall induction rate was 92.31%.The estimated 7-year overall survival ra te and event-free survival (EFS) rate were 76.0% +/- 1.9% and 61.4% +/- 2.1 %, respectively. EFS rates were significantly different among the geographi c areas. In female patients with B-cell precursor (B-pre) ALL and white blo od cell counts at diagnosis (WBCsdiag) below 50.0 x 10(9)/L, favorable outc omes were significant. Favorable outcomes were not significant in B-pre ALL patients with a WBCdiag above 50.0 x 10(9)/L or in T-cell ALL patients. Th e EFS rate fur infants was significantly worse than that for patients over 1 year of age. In B-pre ALL, but not in T-cell ALL, it was found that the h igher the WBCdiag, the worse the EFS rate. Multivariate analysis showed tha t the following factors were significantly unfavorable for EFS: the Philade lphia chromosome, an translocations associated with chromosome 11q23, an ac ute unclassified leukemia, mixed-lineage leukemia, a WBCdiag above 100.0 x 10(9)/L, and male gender. Hyperdiploidy (>50 chromosomes) was significantly favorable for EFS. For further tailoring of treatment and to improve the o utcome in childhood ALL, a prospective large-scale study should be undertak en in Japan. Int J Hematol 2000,72:61-68. (C) 2000 The Japanese Society of Hematology.