Patients with diffuse large B-cell lymphoma are evaluated for risk factors of CNS relapse during initial staging (age \> 60years, lactate dehydrogenase (LDH) \> reference range, clinical stage III/IV, performance status according to Eastern Cooperative Oncology Group (ECOG) \>1, kidney and/or adrenal gland involvement, involvement \> 1 extranodal organ) including evaluation of cerebrospinal fluid.
All patients with systemic DLBCL without CNS involvement are treated with systemic chemotherapy: either 6 cycles of R CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednison) +2xR (rituximab) or 6 cycles of DA EPOCH R (dose adjusted etoposide, prednison, vincristin, cyclophosphamide, doxorubicin) +2xR (rituximab). Patients with ≥ 2 risk factors for CNS relapse or with occult meningeal involvement will be randomized in 1:1 ratio either into arm A with 2 cycles of prophylactic methotrexate 3g/m2 i.v., or into arm B with prophylactic 6x intrathecal methotrexate 12mg (1x intrathecal methotrexate in each cycle of systemic chemotherapy). Patients with 0-1 risk factor will be allocated into arm C without CNS prophylaxis. Patients will be observed for CNS relapse during the follow-up of 1year after the end of the first-line treatment.
