Comparison of molecular alteration in glioblastoma tumors from old and young patients

2056Background: GBM patients (pts.) aged 70 yrs or older have a poorer prognosis than younger pts. IDH1/2 mutations are more prevalent in younger GBM pts. and confer a more favorable prognosis. We compared molecular alterations between younger pts. (YP; 18 = 70), with additional stratification for wild type IDH1/2 status. Methods: GBM tumors submitted for tumor profiling between 2009 and Jan 2016 were tested with NextGen sequencing (SEQ), immunohistochemistry (IHC), fluorescent in-situ hybridization (FISH), fragment analysis (FA) and promoter methylation (Me). Retrospective analysis was performed on 375 GBM’s (YP = 197, OP = 178). Pediatric tumors were excluded. Chi-square was used for exploratory analyses and significance was defined as p < 0.05. Results: Alterations including overexpression of ALK (29% vs. 4.2%), RRM1 (47% vs. 32%) and mutations of ATRX (73% vs. 11%), BRAF (9.3% vs. 1.7%), IDH1 (24% vs. 3%), PDGFRA (7% vs. 0), PTPN11 (6.6% vs. 1%) and TP53 (58% vs....