A brief description follows of the characteristics of these 12 categories of childhood cancer (defined as cancer occurring before age 20) including their associated pathology, epidemiology, and relative survival rates.2,3 Treatment of childhood cancer and late effects associated with disease and treatment are discussed in Chapters 3 and 4.

1. Leukemia Leukemia is the most common childhood cancer, accounting for 25 percent of all cancer occurring before age 20. There are two main types of childhood leukemia—acute lymphoblastic leukemia (ALL), accounting for about three-fourths of leukemias, and acute myeloid leukemia (AML) accounting for much of the remainder of leukemia cases. ALL is a disease of the blood-forming tissues of the bone marrow and is characterized by the overproduction of immature lymphocytes (a type of white blood cell). ALL occurs at all ages, from birth to adulthood, but the peak incidence is between 2 and 6 years of age. In the United States, there is a preponderance of whites and males among children and young adults with ALL. Improvements in treatment have led to remarkable gains in survival, estimated at 79 percent at 5 years. Acute myeloid leukemia, a cancer of the myeloid lineage of white blood cells, occurs at all ages of childhood. The outcome is poorer for AML than for ALL, with a 5-year survival rate of 41 percent.

2. Central nervous system tumors (cancers) and miscellaneous intracranial and intraspinal neoplasms. Central nervous system (CNS) tumors make up the second largest category of neoplasms in children, accounting for 17 percent of childhood cancers. More than half of all CNS malignancies in children and adolescents are a type of brain tumor known as astrocytomas (tumors that arise from star-shaped brain cells call astroctyes). Other common pediatric brain tumors include medulloblastomas (fast-growing tumors usually located in the cerebellum), brain stem gliomas, ependymomas, and optic nerve gliomas. The highest incidence rates of CNS tumors occur among infants and children through age seven. Five-year relative survival rates have improved over time to 67 percent.

3. Lymphomas and other reticuloendothelial neoplasms. Lymphomas (cancers of the lymphatic system) and other reticuloendothelial neoplasms account for 16 percent of childhood cancers. The risks of Hodgkin’s disease and non-Hodgkin’s lymphoma, the major types of cancer in this cat-

2  

The relative survival rate represents the likelihood that a patient will not die from causes associated specifically with the given cancer before some specified time (usually 5 years) after diagnosis. It is always larger than the observed survival rate for the same group of patients.

3  

The intent of this section is to provide a brief overview. It is not intended for a technical audience.



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