Patients then receive adjuvant chemotherapy consisting of cisplatin IV once every 4 weeks for 3 courses beginning on week 11, oral etoposide daily for 21 days every 4 weeks for 3 courses (weeks 11, 15, and 19), cyclophosphamide IV on days 1 and 2 with filgrastim (G-CSF) SQ daily for at least 10 days every 4 weeks for 8 courses (weeks 23-51), and vincristine IV on days 1, 8, and 15 every 4 weeks for 8 courses (weeks 23-51).