Whole Brain Irradiation in Primary Central Nervous System (CNS) Lymphoma (PCNSL)

The aim of the study is to deliver primary systemic high-dose methotrexate (MTX) treatment to PCNSL patients and to define the role of whole brain irradiation (WBI) in primary therapy, i.e., to analyze whether patients who have undergone primary chemotherapy can postpone irradiation with its possible late sequelae until recurrence without incurring losses in progression-free and overall survival. This is studied here for the first time worldwide in a systematic, controlled and randomized manner. In this study, one arm with six cycles of high-dose MTX and subsequent irradiation (A1), which comes closest to a "standard arm of primary therapy", at least according to the majority assessment, is compared to irradiation at recurrence with regard to time to progression and overall survival (A2). In primary therapy failure, it will also be analyzed to what extent salvage therapy with AraC is equivalent to irradiation as the "standard arm" with regard to time to progression and overall survival (arm B1 and B2).