Figure 2

Decision tree algorithm. N, the number of specimens; M, the molecular weight. (A) Decision tree analysis to identify CRC and control specimens. If the peak intensity of an analyzed sample is below the cut-off value at the m/z in the node, the sample proceeds to the left. If not, it proceeds to the right. The cut off value of the peaks were 23.57, 17.42, 3.31 and 0.39, respectively. Red bar, CRC; Blue bar, non-cancerous control. (B) Classification of cancer vs. non-cancerous control specimens by the decision tree algorithm. The cut off value of the peaks were 21.745 and 14.969, respectively. Red bar, cancer; Blue bar, non-cancerous control.