Participants in the cyclophosphamide group will receive etoposide over 1 hour on Days 1-5, cyclophosphamide over 1 hour on Days 2 and 3, and vincristine over 15 minutes on Day 5. This will be repeated every 4 weeks for 6 cycles (24 weeks) of treatment. Mesna, a drug to protect the bladder from the effects of cyclophosphamide, will be given 15 minutes before each dose of cyclophosphamide.