Time dependent ROC analysis shows that the area under the ROC curve (AUC) based on OS is 0.428, 0.681, and 0.851 at 1 year, 3 years, and 5 years, respectively; The AUC based on DSS was 0.454, 0.651, and 0.778 at 1, 3, and 5 years, respectively; The AUC based on PFI was 0.472, 0.853, and 0.824 at 1, 3, and 5 years, respectively, indicating that CD9 has good predictive value for OS, DSS and PFI in ESCC patients at 3 and 5 years (Figures 7A–F). Here, CD9 is linked to esophageal squamous cell carcinoma.