4. Development and validation of a nomogram based on the risk signature

To identify the independent risk factors for OS, univariate and multivariate analyses of the clinical factors and risk score signature were performed. We determined the risk factors that were significant in the univariate analysis, and these significant factors were then included in the multivariate analysis to assess the independent risk factors. Furthermore, an OS-associated nomogram with independent risk factors from the multivariate analysis was designed using the “rms” and the “Hmisc” packages by R software. Calibration curves were drawn, and the concordance index (C-index) was obtained to assess the efficiency of the nomogram. The accuracy of the nomogram in the diagnosis of EC was analyzed by performing tdROC and survival curve analyses. The Kaplan-Meier curves were also used to distinguish the specificity of the nomogram in different subgroups in terms of age, lymph node metastasis (LNM), and recurrence.