Chemotherapy for Childhood Medulloblastoma and Primitive Neuroectodermal Tumors.

Medulloblastoma is the most common form of childhood brain tumor, and management has evolved over the past two decades. Chemotherapy is now an integral part of the treatment of the majority, if not all, patients with this disease. Medulloblastoma is a chemosensitive tumor, and recurrent disease will often respond to a variety of different chemotherapeutic agents. The use of higher-dose chemotherapy supplemented with aggressive hematological support may improve outcome for patients with recurrent disease. The results of prospective randomized trials and large, single, institutional trials in children with newly diagnosed disease suggest that chemotherapy, when given during and after radiotherapy, improves outcome. This is especially true for children with more extensive disease at the time of diagnosis. Event-free survival rates as high as 85% have been reported in children with newly diagnosed medulloblastomas treated with radiation and adjuvant chemotherapy consisting of CCNU, vincristine, and cisplatinum. At the present time, there is no clear evidence that preradiation chemotherapy improves survival for children with medulloblastoma. In fact, two prospective trials suggest that treatment with pre-irradiation chemotherapy may result in poorer overall outcome than treatment with similar doses of radiation therapy or radiation therapy supplemented by postradiation chemotherapy. There is preliminary evidence that chemotherapy may allow for a reduction in the dose of craniospinal irradiation therapy required to control disease, especially for children with nondisseminated disease at the time of diagnosis. Treatment for infants with medulloblastoma and other primitive neuroectodermal tumors remains suboptimal. Some infants and young children will experience long-term disease control after treatment with chemotherapy alone or chemotherapy followed by radiation when the child is older. High-dose chemotherapy supplemented by autologous bone marrow rescue or peripheral stem cell rescue has been utilized in young infants with promising results. The need for postchemotherapy radiation therapy and the volume of radiotherapy required to control disease remain under study.