reported that high mtDNA content showed lower NK-cell frequency and higher IL-2 and TNF-a concentrations, and significantly poorer overall survival and progression-free survival in patients with gliomas after tumor resection, which may be attributed to the abnormal alteration of immune function, this result implied that leukocyte mtDNA content could act as an independent prognostic biomarker in patients with gliomas (59). This evidence concerns the gene TNF and central nervous system cancer.