Childhood cancer is rare, with only approximately 10,000 new cases diagnosed each year in the United States. Nonetheless, cancer is the leading cause of disease-related mortality in children younger than 15 years of age.1 Pediatricians and general practitioners commonly encounter children with vague symptoms that could signal an undiagnosed cancer. The challenge is to identify those children who warrant an evaluation for malignancy. This chapter reviews the typical presentations of the most common pediatric hematologic and solid tumors and provides guidelines for the initial diagnostic evaluation. A review of current therapies and expected outcomes is beyond the scope of this chapter. However, it can be broadly stated that the majority of children diagnosed with cancer can be cured of their disease with currently available treatment.
Cancer results from the uncontrolled proliferation of a clonal cell population, and can arise in essentially any cell type or organ. In general, children with cancer present with symptoms related to the location and extent of the tumor. Cancers cause symptoms by invading or obstructing tissues locally or by spreading to distant sites, leading to pain, organ dysfunction, or both. During childhood, the incidence of specific malignancies varies dramatically with age. The most common types of cancer in children are hematologic malignancies (i.e. leukemias, lymphomas), brain tumors, and extracranial solid tumors, including sarcomas and embryonal tumors.
Because childhood cancer is rare and heterogeneous, the elucidation of its causes is extremely challenging. Certain factors are associated with an increased risk of some types of childhood cancer. For example, in utero exposure to ionizing radiation leads to about a 1.5-fold increased risk of lymphoblastic leukemia.2 External beam radiation, sometimes used to treat patients with solid tumors, is associated with an increased risk of osteosarcoma within the radiation field. Patients with Down syndrome have a 10- to 20-fold increased risk of developing leukemia.3 Several other genetic syndromes are also associated with an increased risk of developing cancer, including neurofibromatosis, Beckwith-Wiedemann syndrome, and Li-Fraumeni syndrome (Table 132-1). However, in the vast majority of children with cancer, no predisposing factors are identified.
TABLE 132-1Common Childhood Genetic Syndromes and Associated Malignancies ||Download (.pdf) TABLE 132-1 Common Childhood Genetic Syndromes and Associated Malignancies
|Genetic Syndrome ||Associated Malignancy |
|Trisomy 21 (Down syndrome) ||ALL, AML |
|Ataxia-telangiectasia ||ALL |
|Familial monosomy 7 ||AML |
|Neurofibromatosis type 1 ||ALL, AML, optic glioma, rhabdomyosarcoma |
|Tuberous sclerosis ||Brain tumors |
|Beckwith-Wiedemann syndrome ||Wilms tumor, hepatoblastoma |
|Li-Fraumeni syndrome ||Osteosarcoma, rhabdomyosarcoma, retinoblastoma |
|Nevus basal cell carcinoma syndrome ||Medulloblastoma, rhabdomyosarcoma, basal cell carcinoma |
|Klinefelter syndrome ||Dysgerminoma |
The incidence of childhood cancer is highest in the first year of life, declines until about age 9 years, and then gradually increases into adulthood. The peak rates of specific childhood malignancies occur at ...