Epidemiology of Acute Childhood Leukemia

Approximately 10,700 children under the age of 15 years are newly diagnosed with cancer each year in the United States (American Cancer Society, 2008), including nearly 3,500 children with leukemia. Even with great advances in treatment over the last several decades, leukemia remains a major source of disease-related morbidity and mortality in children. Of the leukemias, acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML), comprise the vast majority in childhood, occurring at a frequency of approximately 76% and 18%, respectively (Ries et al. 1999). Other leukemias can occur in children, but are extremely rare, including biphenotypic or mixed lineage leukemia, chronic myelogenous leukemia (CML), juvenile myelomonocytic leukemia (JMML), and chronic lymphocytic leukemia (CLL). This review focuses on the epidemiology of childhood ALL and AML. Below, we provide an overview of the classification systems used, including how these entities may help define the timing of when the leukemia might have occurred. Second, international and national data with regard to incidence and survival rates, along with trends, are described. Further, risk factors associated with childhood leukemia are discussed including inherited syndromes, exposures and conditions, and genetic susceptibility as measured through single nucleotide polymorphisms (SNPs). Finally, we discuss challenges and potential future directions that may lead to more fruitful understanding of the underlying causes of childhood leukemia.