Prognostic Nomogram for Advanced Gastric Cancer Treated Beyond Progression with Immune Checkpoint Inhibitors: Evidence from a Single-Center Chinese Study

prognostic stratification for "treatment beyond progression (TBP)" in advanced gastric cancer (GC) patients receiving immune checkpoint inhibitors (ICIs) remains unestablished, particularly in Asian populations. This study aims to develop the first China-specific nomogram integrating multi-dimensional indicators in GC. A retrospective cohort study analyzed 153 advanced GC patients who experienced disease progression after ICI. Kaplan-Meier survival analysis revealed significantly better outcomes in the TBP group, demonstrating superior 6-month overall survival (OS) rates (50.5% vs 30.1%, P = 0.005) and progression-free survival (PFS) rates (34.8% vs 18.6%, P = 0.009). LASSO regression and Multivariate analysis identified CA125 and PLR as independent prognostic factors for OS, while PFS was significantly influenced by LDH, line of therapy, disease stage, and CA125. The developed nomograms demonstrated predictive accuracy, with OS (C-index = 0.676) and PFS (C-index = 0.681) models maintaining consistently high 3-, 6- and 12-month AUC values (0.747–0.765). DCA confirmed clinical applicability, and risk stratification further validated the model's utility, showing markedly superior median OS (10.4 vs 2,9 months, P < 0.001) and median PFS (7.4 vs 2.7 months, P < 0.001) in low-risk versus high-risk patients. This study developed the first OS and PFS nomograms for Chinese advanced GC patients progressing after ICI, providing a prognostic tool for TBP decisions.