Distribution of the cases of test set across the couple of Astrocytoma and brain benign tumor by the selected biomarkers of 22 peaks (2256.76 m/z, 23481.05 m/z, 9198.31 m/z, 22513.91 m/z, 22888.73 m/z, 23087.61 m/z, 4155.28 m/z, 2489.11 m/z, 2246.47 m/z, 2617.14 m/z, 15099.38 m/z, 22666.41 m/z, 29047.13 m/z, 14378.33 m/z, 24002.85 m/z, 2891.43 m/z, 14047.77 m/z, 2006.00 m/z, 14951.04 m/z, 2267.22 m/z, 23672.58 m/z, 22331.29 m/z). When predictive value>0.5, the cases were judged as Astrocytoma; when predictive value≤0.5, the cases were judged as brain benign tumor. In the figure, one case of Astrocytoma and two cases of brain benign tumor were misjudged, and the rest of the cases were all judged correctly