Fig. 4

Diagnostic model construction and assessment. A: Construction of diagnostic model in training set showed entirely differentiation of CRC patients and HV based on three amino acids (Sensitivity: 95.4%; Specificity: 94.4%). B: Testing the diagnostic model in validation set comprising of CRC patients, PC patients and HV shows good ability to differentiate the CRC (Sensitivity: 70.0%; Specificity: 98.7%). C: Testing the diagnostic model in all participates showed high sensitivity and specificity (Sensitivity: 83.3%; Specificity: 96.8%). D: Validating the CEA for CRC diagnosis with clinical cutoff value 5 ng/mL results poor sensitivity for CRC screening (Sensitivity: 31.7%; Specificity: 92.7%)