Five‐Year Unified Risk Prediction Model for Gastric and Esophageal Cancer Based on Nationwide Health Check‐Up Data in Japan: J‐GESS Score

BACKGROUND AND AIM: In Japan, gastric cancer (GC) and esophageal squamous cell carcinoma (ESCC) account for nearly all fatal upper gastrointestinal malignancies. A unified model that simultaneously predicts the incidence of these two cancers could help optimize endoscopic screening and postindex surveillance strategies. METHODS: We conducted a retrospective multicenter cohort study of 33 422 individuals who underwent screening esophagogastroduodenoscopy (EGD) at 17 health check-up institutions across Japan. Clinical and endoscopic data from the index EGD were used to develop a 5-year risk prediction model for GC or ESCC. Significant predictors were identified using Cox regression, and a scoring system (J-GESS score) was constructed by scaling β coefficients. Model performance was evaluated using the 5-year inverse probability of censoring weighted (IPCW) Brier score, calibration, and c indices. Internal validation used bootstrap resampling (500 iterations) to obtain optimism-corrected estimates. Decision curve analysis (DCA) assessed clinical utility at 5 years. RESULTS: At 5 years, the IPCW-estimated cumulative incidence of GC or ESCC was 0.84% (234 events). Independent predictors included older age, male sex, ever smoking, and endoscopic gastric mucosal atrophy. The model showed good calibration at 5 years (calibration-in-the-large 0.005; slope 1.055; identical after optimism correction) and robust discrimination (Harrell's c index 0.81; Uno's 5-year c index 0.81). DCA demonstrated positive net benefit across clinically relevant thresholds. CONCLUSION: Using routinely collected health check-up data, we developed a unified, practical, and internally validated 5-year prediction model for GC and ESCC. The J-GESS score enables effective risk stratification and may inform postindex endoscopic surveillance and screening interval optimization in Japan.