Combination Chemotherapy With or Without Total-Body Irradiation Followed By Stem Cell Transplant in Treating Patients With Non-Hodgkin Lymphoma

RATIONALE: Giving chemotherapy and radiation therapy to the entire body before an autologous peripheral stem cell transplant stops the growth of cancer cells by stopping them from dividing or killing them. The patient's stem cells are then returned to the patient to replace the blood-forming cells that were destroyed by the chemotherapy and radiation therapy. PURPOSE: This phase II trial is studying the side effects of giving combination chemotherapy together with or without total-body irradiation followed by a stem cell transplant and to see how well it works in treating patients with non-Hodgkin lymphoma.