Brain Tumors Across the Age Spectrum: Biology, Therapy, and Late Effects
Section snippets
Epidemiology
The distribution of tumors and tumor locations by age is a fascinating aspect of brain tumor epidemiology.1 For certain tumor types, such as medulloblastoma, ependymoma, and pilocytic astrocytoma, the incidence decreases with age (Fig. 1). Although the differences by age in the proportion of patients with ependymoma is much less than observed for medulloblastoma and low-grade glioma, it is important to note that posterior fossa ependymoma, supratentorial ependymoma, and spinal cord ependymoma
Pathobiology
Medulloblastoma and low-grade gliomas are among the tumors featured in the recent revision of the World Health Organization (WHO) classification of brain tumors.2 An expanded view of medulloblastoma now includes large-cell medulloblastoma, anaplastic medulloblastoma, medulloblastoma with extensive nodularity, and desmoplastic/nodular medulloblastoma in order of decreasing risk of treatment failure using standard therapy. There is increased agreement that these subtypes will be used in the
Disease Presentation
Radiation oncologists are important gatekeepers in the treatment of patients with brain tumors. Critical evaluation of diagnostic information and the ability to choose from a variety of radiation delivery modalities place the radiation oncologist in a position to affect outcome. In the treatment of brain tumors, assessing the extent of resection before radiation therapy serves as a critical example of the radiation oncologist in this pivotal position. Because radiation therapy is generally
Medulloblastoma
Medulloblastoma is first among central nervous system embryonal tumors and malignant brain tumors in children when it comes to understanding the efficacy of available therapy, tumor biology, and the acute and late effects of radiation therapy. After decades of successful treatment using craniospinal irradiation, significant late effects observed in long-term survivors led to trials hoping to reduce or eliminate radiation therapy. Chemotherapy has been successfully used to reduce radiation dose
Late Effects
Understanding where the risks of normal tissue irradiation are high or low can be used effectively in the planning process to minimize the risk or impact of side effects. Patients with brain tumors are vulnerable to wide-ranging side effects from radiation therapy that are magnified in young children and enhanced by tumor and treatments preceding radiation therapy. Side effects range from treatable deficits that rarely impact long-term function to severe and debilitating side effects that
Conclusions
Brain tumor is a well recognized diagnosis in pediatric oncology and these patients represent everything that is positive and negative about current treatment: increasing cure rates, the promise of new treatments, deleterious effects of therapy, and a lack of understanding about the impact of current treatment on long-term survivorship. The impact of long-term sequelae on functional outcome is also important in adults, particularly those with low-grade lesions, who may be expected to have
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