Childhood acute lymphocytic leukemia: progress and problems in treatment.

Acute lymphocytic leukemia is the most common cancer of childhood. A series of total therapy studies begun in 1962 at St. Jude Children's Research Hospital in Memphis, Tennessee has had a dramatic impact on the survival of children with this disease. These studies have systematically examined various drug combinations and radiation therapy in an effort to cure acute lymphocytic leukemia. As a result, a once uniformly fatal condition is now curable in nearly one half of cases. In addition to improved control of the primary disease, refinements in drug treatment and in supportive care have diminished the frequency of severe infections, which may complicate aggressive therapy. Although the quality of life for the survivors so far appears generally good, treatment-induced toxic effects may impose subtle, though significant, handicaps in some cases. A combination of clinical and laboratory investigations begun in the mid-1970s is beginning to demonstrate a previously unknown heterogeneity among patients with acute lymphocytic leukemia. It is now possible to recognize a substantial minority of patients on the basis of these studies as being at "high risk" for treatment failure. For them, drastic modifications of present programs are being investigated in an attempt to improve their prognosis. For patients lacking high-risk features improvements are still needed, but changes in their treatment must be kept within the framework of what is presently successful and must address the hazard of long-term toxicity.