OUTLINE: Patients are stratified according to prior treatment (yes vs no). Patients receive cyclophosphamide IV over 90 minutes on day 1 and filgrastim (G-CSF) subcutaneously beginning on day 3 and continuing until blood counts recover. Treatment continues every 2 weeks for 4 courses in the absence of disease progression or stable disease. Patients who achieve complete remission (CR) after completion of course 4 receive 2 additional courses. Patients who achieve partial remission (PR) after completion of course 4 receive 2 additional courses, and those who achieve CR after completion of course 6 receive 2 additional courses. Patients are followed every 2 months for 6 months, every 6 months for 2 years, and then annually thereafter.