Moreover, we found that EGFR in serum EVs can accurately differentiate high-grade and low-grade glioma patients, and EGFR in EVs positively correlates with ki-67 labeling index (LI), which represents the percentage of ki-67-positive cells in the tumor tissue assessed by immunohistochemistry that has been shown to be associated with the high malignancy and poor outcome of tumors 42-44, indicating that EGFR in serum EVs can reflect the malignancy of glioma. This evidence concerns the gene MKI67 and central nervous system cancer.