Primary CNS lymphoma - an update

Primary central nervous system lymphomas (PCNSL) in immunocompetent patients have long suffered from their rarity. Biological studies as well as initiation of comparative prospective therapeutic studies have been delayed in this population. A significant improvement in survival was observed when radiotherapy was preceded by chemotherapy with high dose methotrexate (MTX). Median survival improved from 16 months, with radiotherapy alone, to 35-45 months with combined treatments, at the cost of a risk of neurological toxicity especially common among people over the age of 60. From then, many studies have attempted to improve outcomes while reducing the toxicity on the central nervous system. If the optimal treatment is not yet established, these studies, mostly retrospective, provide a better understanding of the therapeutic issues to be addressed. Controversies regarding the impact of monoclonal anti-CD 20 antibodies as well as the role and the best modalities of radiotherapy remain and intensive chemotherapy. The latest imaging techniques provide useful elements to rule out differential diagnosis, but histological diagnosis remains mandatory. The evaluation of therapeutic response needs to be improved. Recent biological studies initiated the biological characterization of PCNSL and potential therapeutic targets are identified. Target therapies used in systemic non-Hodgkin's lymphomas have to be tested in PCNSL. PCNSL occurring in the context of immunosuppression are increasingly rare, especially in human immunodeficiency virus (HIV) infected population. They are well characterized in terms of clinical and biological aspects. Epstein-Barr virus (EBV) plays a major role in their lymphomagenesis. Treatment depends mainly on the underlying cause and degree of immunodepression. Whenever possible, similar treatments to those used in immunocompetent PCNSL patients will be offered to immunocompromised patients.