Fig. 2

Receiver operating characteristic (ROC) curves for each single tested biomarker and diagnostic model in different cohorts. Shox2 short stature homeobox 2 gene, ep4 prostaglandin E2 receptor 4 gene (PTGER4), idh1 isocitrate dehydrogenase 1. a–c Comparison of the diagnostic ability of the primary 3-marker model (IDH1 + SHOX2 + PTGER4) and each biomarker in the training cohort, the validation cohort, and the whole cohort, respectively. d Analysis of the diagnostic ability of the primary 3-marker model and the 2-marker models in the whole cohort. e–h Subgroup analysis of the model in the whole cohort. e, f Diagnostic performance in the group of early stage lung cancers and advanced-stage lung cancers, respectively. g, h ROCs of the primary model in the non-Ade lung cancer group (g) and Ade lung cancer group (h)