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Thomas W. McLean and Marcia M. Wofford 21
Childhood cancer is rare; only about 1% of new cancer cases in the United States occur among children younger than 19 years of age. Hematopoietic tumors (leukemia, lymphoma) are the most common childhood cancers, followed by brain/central nervous system (CNS) tumors and sarcomas of soft tissue and bone (Fig. 153-1). There is wide variability in the age-specific incidence of childhood cancers. Embryonal tumors, such as neuroblastoma and retinoblastoma, peak during the first 2 years of life; acute lymphoblastic leukemia peaks during early childhood (ages 2 to 5 years); osteosarcoma peaks during adolescence; and Hodgkin disease peaks during late adolescence (Fig. 153-2). The overall incidence of cancer among white children is higher than that among other ethnic groups and is twice that of African American children in the United States.
Many signs and symptoms of childhood cancer are nonspecific. Although most children with fever, fatigue, weight loss, or limp do not have cancer, each of these symptoms may be a manifestation of an underlying malignancy. Uncommonly a child with cancer will have no symptoms at all. An abdominal mass may be palpated on routine examination, or a complete blood count (CBC) may be unexpectedly abnormal. Some children have a genetic susceptibility to cancer and should be screened appropriately (Table 153-1).