A Phase III Study Of Gemcitabine, Dexamethasone, And Cisplatin Compared To Dexamethasone, Cytarabine, And Cisplatin Plus/Minus Rituximab [(R)-GDP vs (R)-DHAP] As Salvage Chemotherapy For Patients With Relapsed Or Refractory Aggressive Histology Non-Hodgki

RATIONALE: Drugs used in chemotherapy, such as dexamethasone, cisplatin, gemcitabine, and cytarabine, work in different ways to stop cancer cells from dividing so they stop growing or die. Combining chemotherapy with autologous stem cell transplantation may allow the doctor to give higher doses of chemotherapy drugs and kill more cancer cells. Monoclonal antibodies, such as rituximab, can locate cancer cells and either kill them or deliver cancer-killing substances to them without harming normal cells. Giving rituximab as maintenance therapy after stem cell transplantation may kill any remaining cancer cells. It is not yet known which salvage chemotherapy regimen is more effective before autologous stem cell transplantation in treating relapsed or refractory non-Hodgkin's lymphoma.

PURPOSE: This randomized phase III trial is studying salvage chemotherapy using dexamethasone, cisplatin, and gemcitabine to see how well it works compared to dexamethasone, cisplatin, and cytarabine given before autologous stem cell transplantation in treating patients with relapsed or refractory aggressive non-Hodgkin's lymphoma. This trial also is studying giving rituximab as maintenance therapy to see how well it works compared to no further therapy after stem cell transplantation. Rituximab was added to both salvage treatment arms for CD20+ patients in a protocol amendment in 2005.