Diagnosis and treatment of childhood acute lymphoblastic leukemia

Abstract

Acute lymphoblastic leukemia (ALL) is the most common malignancy of childhood, accounting for 25-30% of all pediatric cancer cases. Leukemias arise from genetic changes that occur in a single lymphoid progenitor cell at various stages of maturation, resulting in a clonal expansion. ALL is typically classified by cell surface marker expression as either B-cell progenitor (B-ALL, approximately 85-90% of cases) or T-cell immunophenotype (T-ALL, approximately 10-15% of cases). Childhood ALL can further be subdivided into biologically and prognostically distinctive subsets on the basis of chromosomal abnormalities, molecular genetic aberrations, and early response measures. Over the last 50 years, the prognosis for children with ALL has improved dramatically, with long-term overall survival rates now approximately 90%. The increased cure rate has resulted from a number of factors including (1) development of complex chemotherapeutic regimens designed to achieve clonal eradication; (2) improvements in supportive care; (3) recognition of the central nervous system (CNS) as a sanctuary site; and (4) application and refinement of risk-adapted therapy.