Cancer Health Center

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The molecular signature of pediatric high-grade astrocytomas varies markedly from adult high-grade astrocytomas.[22,23,24] Molecular features of pediatric high-grade astrocytomas are more akin to the genetic aberrations seen in adult glioblastoma that arise from pre-existing lower-grade gliomas (so-called secondary glioblastoma). These include a higher incidence of TP53 mutations, a lower incidence of PTEN and P16^INK4A mutations and the presence of PDGF/PDGFR overexpression. In contrast, IDH mutations have been identified in high frequency in adults with secondary glioblastoma but are rarely seen in pediatric glioblastoma. The incidence of IDH1 mutations rises in children aged 14 years and older.[25]

Prognosis

Low-grade astrocytomas

Low-grade astrocytomas (grade I [pilocytic] and grade II) have a relatively favorable prognosis, particularly for circumscribed, grade I lesions where complete excision may be possible.[26,27,28,29,30] Tumor spread, when it occurs, is usually by contiguous extension; dissemination to other CNS sites is uncommon, but does occur.[31,32] Although metastasis is uncommon, tumors may be of multifocal origin, especially when associated with neurofibromatosis type 1. Unfavorable prognostic features include young age, fibrillary histology, and inability to obtain a complete resection.[33]

High-grade astrocytomas

High-grade astrocytomas are often locally invasive and extensive and tend to occur above the tentorium.[26,29] Spread via the subarachnoid space may occur. Metastasis outside of the CNS has been reported but is extremely infrequent until multiple local relapses have occurred. Biologic markers, such as p53 overexpression and mutation status, may be useful predictors of outcome in patients with high-grade gliomas.[4,34,35] MIB-1 labeling index, a marker of cellular proliferative activity, is predictive of outcome in childhood malignant brain tumors. Both histologic classification and proliferative activity evaluation have been shown to be independently associated with survival.[36] Although high-grade astrocytoma carries a generally poor prognosis in younger patients, those with anaplastic astrocytoma and those in whom a gross total resection is possible may fare better.[30,37,38]

Disease Presentation

Presenting symptoms for childhood astrocytomas depend not only on CNS location, but also size of tumor, rate of growth, and chronologic and developmental age of the child.

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