Primary Central Nervous System Tumors in Children

The standard treatment for children with medulloblastoma, especially those who are older than 3 years of age at the time of diagnosis, includes craniospinal radiation therapy, local radiation therapy, and chemotherapy during and after radiation therapy. The benefits of administering chemotherapy before radiation therapy are unproven, and this approach may result in overall poorer disease control because it delays the initiation of radiation therapy. The amount of radiation therapy needed in patients with nondisseminated disease is unclear. The treatment of children younger than 3 years of age with medulloblastoma is discussed later in this article. The management of brain stem gliomas is currently far from optimal. Surgery has no role in either the diagnosis or the treatment of diffuse intrinsic tumors. Radiation therapy remains the standard treatment for patients with diffuse intrinsic tumors, although the majority die within 18 months of diagnosis. The optimal treatment for exophytic cervicomedullary lesions has yet to be determined. Although surgical resection can result in disease control in many patients, it is often associated with increased neurologic morbidity. Alternative treatments, such as partial resection, followed by focused radiation therapy or chemotherapy may be as effective as complete resection in controlling disease and may result in less morbidity. The treatment of childhood low-grade gliomas is complex, and both the histologic subtype of the tumor and its location must be considered. For some tumors, especially cerebellar astrocytomas, the treatment of choice is total surgical resection. For tumors that are not amenable to gross total resection, radiation therapy remains the standard treatment. Focused radiation therapy may, in time, be significant in the management of children with low-grade tumors, but it is not clear whether such therapy will control the leading edge of the tumor or cause excessive neurologic morbidity. Chemotherapy is being used more and more frequently for children with low-grade gliomas. For the majority of children, it is used to delay the need for more definitive therapy, such as radiation therapy or more aggressive surgical resection. In this regard, it is unclear whether more aggressive chemotherapy is of greater long-term benefit than less aggressive regimens for patients with low-grade gliomas. Clear-cut evidence indicates that chemotherapy, especially the combination of carboplatin and vincristine, is active in low-grade gliomas and delays the need for radiation therapy in the majority of children younger than 5 years of age. The role of chemotherapy in older children is poorly defined. Currently, the standard treatment for children with high-grade gliomas probably includes radiation therapy and chemotherapy with CCNU plus vincristine. Studies are using chemotherapy before radiation therapy in attempts to identify active agents in this disease type. Other active subjects of investigation include the use of high-dose chemotherapy after radiation therapy for children with newly diagnosed disease and the use of radiosensitization agents.