Genetic differences on intracranial versus spinal cord ependymal tumors: a meta-analysis of genetic researches.

Purpose: Although ependymomas occur in both the brain and the spine, the prognosis is quite varied by tumor location. Spinal ependymomas usually follow a relatively benign course with more favorable prognosis than that of the intracranial ependymomas. The aim of this study is to evaluate the genetic differences between spinal ependymomas and their intracranial counterparts using a meta-analysis.
Methods: We searched PubMed, Embase, Web of Science, and the Cochrane library. Comparative or single arm genetic studies that enrolled patients with both intracranial and spinal ependymoma were included. The frequency of genetic aberration was calculated in each group. We calculated the odds ratio (OR) with 95 % confidence intervals (CIs) for direct comparative studies and the logit event rate (LER) and 95 % CI for single arm studies.
Results: Twenty-five studies comprising of 380 spinal ependymomas and 964 intracranial ependymomas were compared to determine the association of the genetic differences of ependymomas at different locations. There were 25 comparable genetic aberrations between spinal and intracranial ependymomas. Among the genes, the NF2 mutation was significantly associated with the spinal ependymomas rather than with the intracranial ependymomas (spinal tumor: LER -0.750, 95 % CI -1.233 to -0.266, intracranial tumor: LER -3.080, 95 % CI -3.983 to -2.177). Intracranial ependymomas were found to be significantly associated with EPB41L3 deletion (OR 0.34; 95 % CI 0.14-0.80) and HIC1 methylation (OR 0.12; 95 % CI 0.02-0.68).
Conclusion: The genetic aberrations of spinal ependymomas are quite different from those of intracranial ependymomas. The difference in prognosis of ependymoma by location may be associated with genetic difference. A more detailed understanding of them may enable the development of targeted therapy and the estimation of prognosis.