MEDICINE Molecular Characteristics of Pediatric Ependymomas: A Systematic Review Monserrat Pérez-Ramírez 1 & Teresa Juárez-Cedillo 2 & Antonio García-Méndez 3 & Normand García-Hernández 1 Accepted: 5 September 2019 # Springer Nature Switzerland AG 2019 Abstract The prognosis for patients diagnosed with ependymoma is relatively poor, with a 5-year overall survival rate of 24– 75%. Currently, tumors are treated by surgical resection followed by radiotherapy, as resection is the most consistent prognostic marker (up to 80%). Therefore, there is a pressing need to improve our understanding of the biology of these tumors and to develop new therapeutic targets. The present work was a systematic review of the current molecular knowledge of pediatric ependymomas. From January 2000 to December 2017, we carried out a search using BMeSH^ (Medical Subject Heading), and Bfree-text^ protocols in the databases Medline/PubMed, SCOPUS, Web of Science, and EMBASE (OVID platform), combining the terms chromosomal alterations, genetic changes, epigenetic changes, and protein expression changes. We selected articles with samples from pediatric patients and chose publications with complete clinical features. Only 33 articles met the criteria for a meta-analysis, suggested by the state of methylation and expression of a characteristic marker of pediatric ependymomas. We found a chromo- somal alteration and one gene associated with survival; these are candidates for bad prognosis biomarkers. Keywords Ependymoma . Molecular characteristic . Systematic review . Pediatric patients Introduction Ependymoma (EP) arises from the ependymal cells of the fourth cerebral ventricle and the spinal cord. These tumors can develop in both adult and children patients; however, intracranial EP occurs more frequently in children, whereas spinal EPs are more frequent in adults. These tumors are clas- sified by their location as infra and supratentorial EPs [1]. EP is the third most common pediatric tumor of the central nervous system and the prognosis is relatively poor for pa- tients with this diagnosis, with a 5-year overall survival rate of 24–75%; therefore, EPs are considered a public health problem. These tumors are treated with surgical resection followed by radio- and chemotherapy. Actually, resection is the best prognostic marker (up to 80%) used for clinical diag- nostic; therefore, it is necessary to understand the tumorigen- esis of EP in order to develop new therapeutic targets [2, 3]. The clinical features of EPs used for prognosis—such as pa- tient age, tumor location, extent of surgical resection, and tumor histopathology grade—are insufficient and have inconsistent re- sults, so it is necessary to come up with strategies to improve treatment and provide an exact prognosis [4, 5]. Several studies have suggested that epigenetic silencing of tumor suppressor genes and expression changes are an important mechanisms of EP pathogenesis in supratentorial and spinal tumors [2]. In this systematic review, we aimed to determine the mo- lecular characteristics of these tumors that may establish tumor markers. This article is part of the Topical Collection on Medicine * Normand García-Hernández normandgarcia@gmail.com 1 Unidad de Investigación Médica en Genética Humana, Hospital de Pediatría BDr. Silvestre Frenk Freud,^ Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Av. Cuauhtémoc 330, Col. Doctores, Del. Cuauhtémoc, 06720 Ciudad de México, Mexico 2 Unidad de Investigación Epidemiológica y en Servicios de Salud, Área Envejecimiento, CNM Siglo XXI, IMSS, Actualmente Comisionada en Unidad de Investigación en Epidemiología Clínica, Hospital Regional núm. 1 Dr. Carlos MacGregor Sánchez Navarro, IMSS, Colonia Del Valle, Delegación, Benito Juárez, 03100 Ciudad de México, Mexico 3 Neurocirugía Pediátrica, Hospital General BDr. Gaudencio González Garza,^ Centro Médico Nacional BLa Raza^, Instituto Mexicano del Seguro Social, Calzada Vallejo y Jacarandas S/N, Col. La Raza, Del. Azcapotzalco, 02980 Ciudad de México, Mexico https://doi.org/10.1007/s42399-019-00147-5 SN Comprehensive Clinical Medicine (2019) 1:861–868 /Published online: 24 October 2019