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.