Comparable outcomes of radiation therapy without high-dose methotrexate for patients with primary central nervous system lymphoma

Background: The previous trials of radiotherapy conducted for primary central nervous system lymphoma (PCNSL) have not been successful. Therefore, we have investigated the clinical outcomes and the role of radiation therapy in the treatment of PCNSL. Methods: Thirty-three consecutive patients with PCNSL treated with cranial radiotherapy (3040 Gy whole brain plus 10-20 Gy boost) without administration of high-dose methotrexate were retrospectively analyzed. Nine patients received whole spinal irradiation (WSI) as an additional therapy. The median age of patients was 58 years (range: 28-78 years), and 70% showed a poor performance status (PS). Results: The median survival time (MST) was 13 months, and the 5-year overall survival rate was 35%. The initial response and the number of tumors were significant prognostic factors, and WSI tended toward significance in a multivariate analysis. Four of five patients, who received prophylactic WSI, were 4-year survivors without a tumor relapse and none of them had tumor involvement in the vertebral canal. One patient developed radiation-induced brain necrosis, however, WSI did not seem to affect the late complications. Conclusions: We consider it important to reduce severe acute and late complications in patients qualified for receiving an aggressive therapy, and to explore the possible tolerable and curative treatment methods that can be used in order to improve the prognosis for PCNSL. Further modifications, including the application of WSI seem to be necessary in the management of PCNSL.