Tailoring Treatment for B Cell Non-hodgkin's Lymphoma Based on PET Scan Results Mid Treatment

The purpose of this study is to assess whether patients who are likely to fail R-CHOP, as predicted by a mid-treatment PET scan, can have an improved outcome if switched to a standard salvage regimen R-ICE (rituximab, ifosfamide, carboplatin, etoposide). Patients who have a negative PET scan after 4 cycles of R-CHOP have an excellent prognosis (\>85% chance of cure) and should complete treatment with 6 cycles of standard R-CHOP. Patients who have a positive PET scan after 4 cycles of R-CHOP have a very poor prognosis (\~10% chance of cure) and may have an improved outcome if switched to a non-cross resistant chemotherapy combination R-ICE.