Acute Lymphoblastic Leukemia in Children

Approximately 6000 cases of acute lymphoblastic leukemia (ALL) are diagnosed in the United States annually; half the cases occur in children and teenagers. In the United States, ALL is the most common cancer among children and the most frequent cause of death from cancer before 20 years of age. 1,2 Presenting symptoms of ALL include bruising or bleeding due to thrombocytopenia, pallor and fatigue from anemia, and infection caused by neutropenia. Leukemic infiltration of the liver, spleen, lymph nodes, and mediastinum is common at diagnosis. Extramedullary leukemia in the central nervous system (CNS) or testicles may require specific modifications in therapy. Since the first description in 1948 of temporary remission of leukemia induced by chemotherapy, 3 pediatric ALL has provided a model for improvement of survival among patients with cancer by progressive improvements in the efficacy of multi-agent chemotherapy regimens and by stratification of treatment intensity according to the clinical features of the patient, the biologic features of the leukemia cells, and the early response to treatment, all of which are predictive of the risk of relapse. Collectively, these advances have increased the survival rate from less than 10% in the 1960s to 90% today (Fig. 1). New discoveries are revealing the promise and challenges of precision-medicine strategies that integrate leukemia genomics into contemporary therapy.