Primary Central Nervous System Lymphoma.

Standard therapy does not exist for the treatment of primary central nervous system lymphoma. This is because of low patient numbers, slow accrual to clinical trials, and the absence of phase III randomized clinical trials. Neuro-oncologists agree that whole brain irradiation alone is no longer the best treatment option; treatment should include high-dose methotrexate chemotherapy, and treatment strategies must combine efficacy without untoward toxicity. However, beyond this, there is no widespread consensus. Significant neurocognitive toxicity has been associated with combined chemotherapy-radiation regimens, especially in elderly patients. This has prompted many to defer radiation therapy in all patients except those that refuse chemotherapy, those that have a partial response to chemotherapy, or those that have disease progression through chemotherapy. There is supporting evidence for this approach; however, confirmatory data from multicenter clinical trials and 5-year survival rates are unavailable. This underscores the importance of ongoing clinical trials.