A Study of Two Associations of Rituximab and Chemotherapy, With a PET-driven Strategy, in Lymphoma

1\) Induction Arm A: 4 cycles of R-ACVBP, 2 weeks interval. After the 3rd cycle, if PET 2+ (fixing), collection of peripheral blood stem cell progenitors will be organized at the time of hematological recovery under support with G-CSF. The consolidation treatment will depend on results of PET evaluation after cycle 2 (PET2) and cycle 4 (PET4). * Consolidation 1A (in case of PET 2- PET 4 -): * High-dose Methotrexate with folinic acid rescue; 2 cycles spaced out 14 days. * Rituximab-Ifosfamide-Etoposide : 4 cycles spaced out 14 days * Cytarabine sub-cutaneous, during 4 days; 2 cycles spaced out 14 days. * Consolidation 2 A (in case of PET 2+ PET4 -): * 2 cycles high-dose Methotrexate with folinic acid rescue * High dose with Z- BEAM conditioning regimen followed by autologous transplant. * Salvage(in case of PET 4 +): The patient will be treated with a salvage regimen, after a biopsy of the residual mass whenever possible. 2\) Induction arm B: 4 cycles of R-CHOP, 2 weeks interval. After the 3rd cycle, if PET 2+ (fixing), collection of peripheral blood stem cell progenitors will be organized at the time of hematological recovery under support with G-CSF. The consolidation treatment will depend on results of PET evaluation after cycle 2 (PET2) and cycle 4 (PET4). * Consolidation 1B(in case of PET 2- PET 4 -): 4 additional cycles of R-CHOP, 2-weeks interval * Consolidation 2 B(in case of PET 2+ PET 4 -): * 2 cycles high-dose Methotrexate with folinic acid rescue * High dose with Z- BEAM conditioning regimen followed by autologous transplant * Salvage(in case of PET 4 +): The patient will be treated with a salvage regimen, after a biopsy of the residual mass whenever possible