A previous study using bioinformatical analysis of the Rembrandt or TCGA database showed that high IDO1/TDO mRNA expression was associated with poor prognosis in patients with glioma.13,35,40 Herein, for the first time, it was found that glioma patients with positive IDO1/TDO protein expression had shorter overall survival. Here, IDO1 is linked to central nervous system cancer.