OBJECTIVES: I. Determine the feasibility of high-dose cyclophosphamide and filgrastim (G-CSF) in patients with stage IV, relapsed, or progressive low-grade follicular non-Hodgkin's lymphoma. II. Determine the toxic effects of this regimen in these patients, including those with marrow involvement. III. Determine the rates of complete remission (CR) and partial remission and time to failure in previously treated and untreated patients. IV. Determine the effectiveness of this regimen in eradicating bcl-2 rearrangements, as determined by polymerase chain reaction (PCR), in previously untreated patients. V. Correlate the duration of CR to PCR results in responding patients.