Figure 3: GBM-associated changes in metabolites could affect survival. The significantly different metabolites between GBM and controls were analyzed using a Kaplan-Meier analysis. Three metabolites; mannitol (a), pyroglutamine (b) and 7-methylguanine (c) that were significantly different in pre-radiation (pre- RT) samples (as shown in the ratio), compared to controls, are plotted as a survival curve. Metabolite values across all the pre-RT samples were divided into four quartiles based on the median value. The first quartile (qt1) values were compared to the fourth quartile (qt4) values. The differences were significant, as shown in the respective p values. PFS: progression free survival.