Improved therapy for children with acute lymphoblastic leukemia

We have examined the factors influencing clinical prognosis in Japanese children with B-precursor acute lymphoblastic leukemia (ALL), who have been treated in consecutive chemotherapeutic trials from 1976 to 1995. During this time the results of treatment have steadily improved in children with average presenting features (age 1–10 years old and leukocyte counts > 50,000/μL). The 4-year event-free survival (EFS) estimates now exceed 85% in our current trials. Furthermore, high-dose methotrexate and intrathecal therapy could be substituted for cranial irradiation without an increase of central nervous system relapse rate. However, children with unfavorable presenting features (leukocyte counts ≥ 50,000/μL; high-risk group) have a worse prognosis, although there is some improvement of outcome. The patients in the high-risk group have obtained the 4-year EFS rate of better than 60%. Further investigations of prognostic factors in ALL focused on the biological features may permit identification of groups of children at risk of very poor outcome. In the patient cohorts consistently resistant to chemotherapy, the hazards of more intensive treatment such as bone marrow transplantation may be outweighed by the possible benefits.