For patients with stage I lung cancer, CTAPIII/CXCL7 had the highest AUC (Fig. 3A, training set: AUC 0.778, 95% CI: 0.698–0.858; Fig. 3B test set: AUC 0.729, 95% CI: 0.607–0.787). The gene discussed is PPBP; the disease is lung carcinoma.