2018 Volume 27 Issue 12 Pages 906-913
The standard treatment for primary central nervous system lymphoma (PCNSL) is high-dose methotrexate (HD-MTX) and whole brain radiotherapy (WBRT). However, relapse rates are high despite remission after initial treatment, and there is no effective standard treatment for recurrent PCNSL. We aimed to determine the effectiveness of gamma knife stereotactic radiosurgery (GK surgery) for recurrent PCNSL and to clarify its acceptability as salvage treatment at the time of relapse.
We performed a retrospective analysis of patients who underwent salvage GK surgery for recurrent PCNSL from October 2010 to May 2017. The radiographic response of target lesions, the median progression-free survival, the median overall survival, the median overall survival from initial treatment, and any adverse events after GK surgery were assessed as endpoints. In total, 13 patients with 109 target lesions were treated with GK surgery : seven were initially treated with both HD-MTX and WBRT (mean age, 59.7 years), and six were initially treated with only HD-MTX (mean age, 79.5 years). The mean period from initial treatment to the first GK surgery was 9.8 months, the mean target tumor volume was 3.0 cm3, and the mean marginal dose was 12.6 Gy (this was prescribed to the 50% isodose line that encompassed the target volume).
Of the 109 lesions, 87 achieved complete response (84%) over a mean period of 1.8 months. The response rate was 91%. Although radiation necrosis occurred in 10 lesions (9%), all cases were asymptomatic according to the Common Terminology Criteria for Adverse Events (i.e., Grade 1). From the first GK surgery, median progression-free survival was 7 months (5 months in the HD-MTX+WBRT group and 7 months in the HD-MTX group) and median overall survival was 19 months (19 months in the HD-MTX+WBRT group and 51 months in the HD-MTX group). The median overall survival from initial treatment was 47 months (47 months in the HD-MTX+WBRT group and 52 months in the HD-MTX group).
In conclusion, GK surgery has fewer adverse events while retaining comparable median progression-free survival and median overall survival to other treatments. Alternative treatments for recurrent PCNSL are chemotherapy with rituximab or temozolomide and high-dose chemotherapy combined with autologous stem cell transplantation. GK surgery benefits from showing a high remission rate and immediate effect for recurrent PCNSL, while being relatively safe and less invasive. Overall, GK surgery appears to be a safe and effective option for salvage treatment in patients with recurrent PCNSL, even after WBRT and when treating the elderly.
