Helicobacter pylori virulence gene expression defines a stage-associated transcriptional signature in gastric cancer

Figure 4 Discrimination, incremental value, and calibration of the combined four-gene transcriptional signature (n = 159). A: Discrimination across model specifications was evaluated using receiver operating characteristic area under the curve (AUC) for distinguishing early (stages I-II) from advanced (stages III-IV) cases. The four-gene panel alone achieved AUC = 0.747 (cross-validated), vs AUC = 0.49 for the clinical-variables-only model. The dotted reference line represents chance-level discrimination (AUC = 0.5); B: Calibration assessed by comparing the observed proportion of advanced-stage (III-IV) cases to the mean model-predicted probability across five equal-sized bins of pooled out-of-fold predicted probabilities. The dashed diagonal line indicates perfect calibration. Calibration was adequate (Hosmer-Lemeshow χ² = 5.53, df = 3, P > 0.05). AUC: Area under the curve; ROC: Receiver operating characteristic; CV: Cross-validation.