The Role of Neuroaxis Irradiation in the Treatment of Intraspinal Ewing Sarcoma: A Review and Meta-Analysis

SIMPLE SUMMARY: Primary extraosseous intraspinal Ewing sarcoma (EwS) is a rare disease and optimal treatment strategies remain unclear. Most patients undergo trimodal therapy consisting of surgery, chemotherapy and radiation therapy. In this study, we focus on the role of radiation therapy in the treatment of EwS, specifically the use of craniospinal irradiation (CSI). We identified 24 patients with intraspinal EwS treated with CSI. A majority of these patients achieved complete remission. We found that patients with multiple lesions at time of diagnosis and intradural tumor location were more likely to undergo CSI while patients with a single lesion received focal irradiation more often. In spite of this imbalance, there was no difference in survival outcome between treatment groups. In summary, CSI is a valuable option in the treatment of EwS and should be considered individually based on tumor and patient characteristics. ABSTRACT: The role of cranio-spinal irradiation (CSI) for primary extraosseous intraspinal Ewing sarcoma (EwS) remains unclear. Here, we evaluate clinical and survival outcomes in patients with primary intraspinal EwS treated with CSI as part of multimodal primary therapy regimens. We abstracted patient information, including details on treatment application, efficacy, and tolerance from the literature and our hospital database for a cohort of 24 primary intraspinal EwS patients treated with CSI. Median age was 25.5 years, median CSI dose was 36 Gy and mean boost dose was 12.8 Gy. Sixteen patients (66.7%) achieved complete radiological remission, another 5 patients demonstrated partial response and 1 patient showed no response to treatment. Compared to a cohort of patients treated with focal radiotherapy, CSI patients were more likely to have multifocal disease at time of diagnosis (p = 0.001) and intradural tumor location (p < 0.001). Despite over-representation of these unfavorable characteristics, there was no survival difference between groups (p = 0.58). While CSI shows promising results in the treatment of primary intraspinal EwS, treatment should be considered individually based on tumor and patient characteristics in the absence of prospective trials.