Optimal current treatment of childhood acute lymphoblastic leukemia.

The treatment of childhood acute lymphoblastic leukemia (ALL) has been remarkably successful over the past 30 years of the chemotherapy era. A substantial proportion of patients, perhaps 40%-50%, are apparently cured with currently available therapy. However, optimal therapy has not yet been devised because of substantial therapeutic failures in the form of relapse and unacceptable side effects. Remission induction therapy is the most settled aspect of therapy. The addition of asparaginase or an anthracycline to prednisone and vincristine is highly effective. Preventive central nervous system therapy is under revision and study, with a variety of approaches likely to prove equally effective. Continuation (maintenance) therapy is in the most need of revision because a majority of therapeutic failures are due to bone marrow relapse--the failure of systemic therapy to prevent emergence of resistant leukemia cells. The optimal duration of therapy has not been established, the relapse after cessation of therapy lasting 2-3 years currently being 20%-25%. Bone marrow transplantation during remission shows promise as a therapeutic modality. The most promising development, however, is our increasing understanding of biological subpopulations of leukemia cells. This ultimately may help us develop more effective and specific therapy for childhood ALL.