Clinical and Molecular Features of Disseminated Pediatric Low Grade Glioma - A Systematic Review of Literature
Abstract INTRODUCTIONGliomas account for approximately 46% of all pediatric CNS tumors. There is growing awareness of pediatric low-grade gliomas (PLGG) that disseminate to distant parenchymal or leptomeningeal locations either at the time of initial diagnosis or upon disease surveillance. Disseminated PLGGs (dPLGGs) are associated with a poorer prognosis than non-disseminated PLGGs. To date there is no comprehensive report characterizing the genome profile of dPLGGs and their associated management. This systematic review aims to identify the pattern of genetic alterations and treatment outcomes described for dPLGG.METHODSA systematic review of the literature was performed to identify relevant articles. A quality and risk of bias assessment of articles was done using the GRADE framework and ROBINS-I tool, respectively.RESULTSFifty-two studies published from 1994 to 2020 were included in this review with 368 cases reported. There was sporadic reporting of genetic alterations. The most common genetic alteration observed among study subjects was 1p deletion (76%) and BRAF-KIAA1549 fusion (55%). BRAF p.V600E mutation was found in 7% of subjects. A higher proportion of cases demonstrated primary dissemination compared to secondary dissemination (65% vs 25%). First-line chemotherapy consisted primarily of an alkylation-based regimen and vinca alkaloids. Surgical intervention ranged from biopsy alone to surgical resection and CSF diversion, and depended largely upon tumor location and timing of dissemination. Overall, 73% of cases were alive at last follow-up (median, 40.2 months). All studies reviewed either ranked low or moderate for both quality and risk of bias assessments. CONCLUSIONWhile 1p deletion and BRAF-KIAA1549 fusion are the most commonly described molecular alterations in dPLGG, these tumors appear to express heterogeneous molecular and biological characteristics distinct from non-disseminated PLGGs. Additional studies on the molecular and biological features of these tumors are needed to better understand the pathogenesis of dPLGG and to inform the development of additional targeted regimens.