PVT1 and central nervous system cancer: Furthermore, univariate Cox regression analysis of overall survival of glioma samples within TCGA showed that high PVT1 expression (P <0.001), low HAR1A expression (P <0.001), increased age (both P <0.001), high karnofsky performance score (KPS; both P <0.001) and WHO grade (all P <0.001 for II/IV and III/IV), and advanced histological types (all P <0.001 for OD/GBM, OA/GBM and A/GBM) were the risk factors associated with prognosis (Table 1).