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

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.

Keywords: craniospinal irradiation; intraspinal Ewing sarcoma; multimodal therapy; overall survival; radiotherapy.

Figure 1

Flow chart of the report selection process. The database resources included: Cochrane Library, PubMed, Ovid MEDLINE Research platforms, and the NIH clinical trials register (https://clinicaltrials.gov/) (accessed on 4 October 2021). The following search terms were used: Ewing Sarcoma, peripheral neuroectodermal tumor, thoracal spine, lumbar spine, intraspinal Ewing sarcoma, cranio-spinal irradiation.

Figure 2

Kaplan–Meier survival curves of EwS patients with multiple intraspinal lesions at time of diagnosis compared to singular tumors (A) and with intradural compared with extradural/epidural tumors (B). Patients with multiple lesions tended to do substantially worse compared to those with singular tumors (p = 0.052). Intradural tumors were more likely to be associated with a worse prognosis (p = 0.25).

Figure 3

Kaplan–Meier survival curves of patients with intraspinal EwS treated either with CSI or focal RT. No significant difference between cohorts was observed (p = 0.58).

Figure 4

MRI and PET-CT scans of lumbar EwS before and after definitive RCth (radiochemotherapy) and ASCT (autologous stem cell transplantation). (A) Initial T1-weighted sagittal MRI of the thoracic and lumbar spine with intramedullary tumor; (B) T1-weighted sagittal MRI with residual post-therapeutic signal alterations; (C) post-therapeutic PET-CT scan with no residual increased FDG uptake.