The Diagnosis and Treatment of Primary CNS Lymphoma

Background: Primary central nervous system lymphoma is a diffuse large B-cell lymphoma with exclusive manifestation in the central nervous system (CNS), leptomeninges, and eyes. Its incidence is 0.5 per 100 000 persons per year. Currently, no evidence-based standard of care exists. Methods: This review is based on pertinent publications (2000-2017) retrieved by a selective search in PubMed. Results: The clinical and neuroradiological presentation of primary CNS lymphoma is often nonspecific, and histopathological confirmation is obligatory. The disease, if left untreated, leads to death within weeks or months. If the patient's general condition permits, treatment should consist of a high-dose chemotherapy based on methotrexate (HD-MTX) combined with rituximab and other cytostatic drugs that penetrate the blood-brain barrier. Long-term survival can be achieved in patients under age 70 by adding non-myeloablative consolidation chemotherapy or high-dose chemotherapy with autologous stem cell transplantation (HD-AST) to the induction therapy. Clinical trials comparing the efficacy and toxicity of these two treatment strategies are currently underway. Consolidation whole-brain radiotherapy is associated with the risk of severe neurotoxicity and should be reserved for patients who do not qualify for systemic treatment. Some 30% of patients are refractory to primary treatment, and at least 50% relapse. In patients who are still in good general condition, relapse can be managed with HD-AST. Re-exposure to conventional HD-MTX-based polychemotherapy is another option, if the initial response was durable. The 5-year survival rate of all treated patients is 31%, according to registry data. Conclusion: Current recommendations for the treatment of primary CNS lymphoma are based on only a small number of prospective clinical trials. Patients with this disease should be treated by interdisciplinary teams in experienced centers, and preferably as part of a controlled trial.