Stem Cell Transplantation With or Without Rituximab in Treating Patients With Relapsed or Progressive B-Cell Diffuse Large Cell Lymphoma

OBJECTIVES: * Compare disease-free survival of patients with relapsed or progressive B-cell diffuse large cell lymphoma undergoing stem cell transplantation with or without post-transplant rituximab. * Evaluate the effect of rituximab, administered post-transplant, on the procedure-related mortality of these patients. * Determine the potential infectious complications of the addition of this drug to autologous stem cell transplantation in these patients. * Compare overall survival of patients treated with these regimens. OUTLINE: This is a randomized, multicenter study. Patients are stratified according to relapse (relapsed more than 6 months after either initial complete remission \[CR\] or CR with positive positron emission tomography or MRI \[gallium\] vs failed to achieve initial CR or relapsed within 6 months after either initial CR or CR with positive PET or MRI \[gallium\]) and prior rituximab (yes vs no). Stem cell mobilization * Patients receive rituximab IV over 4-8 hours on days 1 and 5. Patients also receive cyclophosphamide IV over 2 hours on day 8 and filgrastim (G-CSF) subcutaneously (SC) beginning on day 9 and continuing until the last day of apheresis. Stem cells are collected over 1-3 days. Preparative regimen * Regimen A (patients who have received prior radiotherapy or are ≥ 61 years of age): Patients receive carmustine IV over 2 hours on day -6, etoposide IV over 4 hours on day -4, and cyclophosphamide IV over 2 hours on day -2. * Regimen B (all other patients): Patients undergo total body irradiation twice daily on days -8 to -5. Patients receive etoposide IV over 4 hours on day -4 and cyclophosphamide IV over 2 hours on day -2. Stem cells are reinfused on day 0. Patients are then randomized to one of two post-transplant treatment arms. Post-transplant treatment * Arm I (rituximab): Patients receive G-CSF SC beginning on day 6 and continuing until blood counts recover. Patients receive rituximab IV over 4-8 hours every 7 days for 4 doses, starting on day 45 post-transplant. Course of rituximab is repeated beginning on day 180 post-transplant. * Arm II (no rituximab): Patients receive G-CSF as in arm I. Patients are followed for 10 years. PROJECTED ACCRUAL: A total of 427 patients will be accrued for this study within 3.5 years.