Consolidation Treatment for Primary Central Nervous System Lymphoma: Which Modality for Whom?

Primary central nervous system lymphoma is a rare aggressive disease that largely affects elderly patients and is associated with poor prognosis. The optimal treatment approach is not yet defined and it consists of induction and consolidation phases. The combination of high-dose (HD) methotrexate-based chemotherapy followed by whole-brain radiotherapy (WBRT) prolongs the median progression-free survival (PFS) and overall survival 2- to 3-fold as compared to WBRT alone but is associated with significant delayed neurotoxicity. Alternative strategies are being investigated in order to improve disease outcomes and spare patients the neurocognitive side effects. These include reduced-dose WBRT, non-myeloablative HD chemotherapy, or HD chemotherapy with autologous stem cell transplantation (HDC/ASCT). There are no randomized studies that compare all these consolidation regimens head to head but recently HDC/ASCT has been evaluated versus WBRT in prospective randomized studies. These studies proved that WBRT and HDC/ASCT yield similar 2-year PFS with preserved or improved cognitive function after HDC/ASCT. Yet, the proportion of patients treated with such intensive consolidation is low, both in real life and in specialized centers, leaving many unsettled issues. This review is appraising current dilemmas related to the choice of consolidating therapeutic modalities, their associated acute and delayed toxicity, and future prospects for alternative approaches in the elderly.