Radiation Therapy Plus Combination Chemotherapy in Treating Children With Medulloblastoma

OBJECTIVES: I. Assess whether a cyclophosphamide-containing combination chemotherapy regimen increases progression-free survival compared to a lomustine-containing regimen in children with newly diagnosed, average-risk medulloblastoma. II. Determine progression-free and overall survival of children treated with craniospinal radiotherapy and local boost radiotherapy for a total dose of 5580 cGy followed by adjuvant lomustine/cisplatin/vincristine vs. cyclophosphamide/cisplatin/vincristine. III. Determine the long-term neurocognitive, endocrinologic, and cardiopulmonary sequelae associated with craniospinal radiotherapy, local boost radiotherapy, and adjuvant chemotherapy in these children, and determine whether replacement of lomustine with cyclophosphamide alters the incidence and degree of sequelae. IV. Determine whether cellular and biologic parameters, including tumor molecular genetic analysis, DNA ploidy, mitotic activity markers, and immunohistochemical analysis, are correlated with progression-free survival, overall survival, and patterns of disease relapse in these patients. V. Evaluate the utility of routine magnetic resonance imaging surveillance studies of the head and spine in detecting subclinical recurrent disease. OUTLINE: This is a randomized study. Patients are stratified by participating institution. Following surgery, patients are randomized to one of two groups. The first group receives craniospinal irradiation followed by a boost to the primary tumor. Beginning within 1 week after initiation of radiotherapy, patients receive vincristine weekly for 8 doses. Beginning 6 weeks after the completion of radiotherapy, patients receive adjuvant lomustine/vincristine/cisplatin every 6 weeks for a total of 8 courses. The second group receives craniospinal irradiation plus vincristine as above, followed by adjuvant cyclophosphamide/vincristine/cisplatin every 6 weeks for a total of 8 courses. Patients are followed every 3 months for 1 year, every 6 months for 2 years, then annually. PROJECTED ACCRUAL: It is anticipated that 240-300 patients will be entered over 4 years.