S0350 Combination Chemotherapy in Treating Patients With Newly Diagnosed Stage II, Stage III, or Stage IV Peripheral T-Cell Non-Hodgkin's Lymphoma

RATIONALE: Drugs used in chemotherapy, such as cisplatin, etoposide, gemcitabine, and methylprednisolone, work in different ways to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. Giving more than one drug (combination chemotherapy) may kill more cancer cells. PURPOSE: This phase II trial is studying how well combination chemotherapy works in treating patients with newly diagnosed stage II, stage III, or stage IV T-cell non-Hodgkin's lymphoma.