Primary research question
Randomisation R1 (for all patients in the main study cohort): Can the cumulative incidence for recurrences with CNS involvement (CNS recurrence, pCICR) be reduced by an induction phase in which the three-week standard glucocorticoid therapy with prednisone (60mg/m²/d) plus tapering over 9 days is replaced by a 2-week dexamethasone treatment (10mg/m²/d)?
Randomisation R2 (for high-risk patients in the main study cohort): For these patients, can the probability of event-free survival (pEFS) be improved by the intensified treatment arm (protocol Ib* and intensified protocol M) compared to the standard treatment arm (protocol Ib and protocol M)?
Secondary research question
the pEFS and the cumulative incidence of recurrence/CNS recurrence compared to the EURO-LB 02 clinical trial
overall survival (OS), defined as the time from diagnosis to death (of any cause) or to the date of last contact with living patients compared to the EURO-LB 02 study
treatment-related mortality in the randomised arms and in comparison to EURO-LB02
the profile of adverse events and serious adverse events in protocol-specific elements, in the randomisation arms, during follow-up and in comparison to EURO-LB02
the feasibility and results of risk stratification
the identification of prognostic molecular markers for T-LBL
the feasibility of evaluating minimal residual disease (MRD) in children and adolescents with LBL
