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Central nervous system (CNS) neoplasms are, as a group, the most
common solid tumors of childhood, second only to the leukemias as
a cause of cancer in children. Despite improvements in diagnosis
and management, more children will die of brain tumors than of any
other type of pediatric cancer.1 Although the prognosis
for children with certain CNS tumors, such as medulloblastoma,2 has
been improved through a combination of surgical advances and refinements
in radiotherapy and chemotherapy, other groups, such as diffuse
intrinsic brainstem gliomas,3 continue to have a poor outcome.
Children who experience long-term survival after therapy are at
risk for sequelae from the tumor or its treatment that may adversely
impact their quality of life.4 Current cooperative group
studies are attempting to address these issues, focusing on improving
survival results, with treatment-responsive lesions, in children
with tumor types that historically have been resistant to therapy,
as well as on improving quality of life in children with tumor-responsive
lesions. Increasingly, these studies also incorporate molecular
and biological classification of tumors to facilitate risk-adapted
treatment stratification.
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Epidemiology
and Risk Factors
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Brain tumors occur at an incidence of 3.1 per 100,000 children
per year. There is no gender bias, with a male-to-female ratio of
1.2:1.0 in Caucasian children and 0.9:1.0 in African American children. The incidence
of brain tumors, as reflected in data from the Surveillance, Epidemiology,
and End Results (SEER) Registry of the National Cancer Institute
and the Central Brain Tumor Registry of the United States (CBTRUS),
has increased over the past 30 years. While some absolute increase
in childhood brain tumors may exist, an analysis of the data, which
identified a 35% increase in pediatric brain tumors between 1973
and 1994, demonstrated a jump in the incidence of brain tumor diagnoses
in the mid-1980s coincident with the introduction of the routine
use of magnetic resonance imaging (MRI), suggesting improved detection
of previously undiagnosed lesions (eg, an increase in the diagnosis
of tectal gliomas by MRI, which had previously been diagnosed as
idiopathic aqueductal stenosis).
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Genetic Causes
of Brain Tumors
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A variety of familial syndromes and diseases have been identified
that predispose the patient to a variety of brain and other tumors.
The most common of these disorders is neurofibromatosis 1 (von Recklinghausen
disease). Additional disorders include neurofibromatosis 2, tuberous
sclerosis complex (TSC), Von Hippel-Lindau (VHL) disease, Cowden
disease, Li-Fraumeni syndrome, Turcot syndrome, and Gorlin syndrome.
Summary information on each of these syndromes is detailed in eTable 460-1.
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