Abstract
Background: The prognosis of esophageal and gastric carcinoma in situ (CIS) is excellent but population-level incidence pattern and mortality determinants remain limited. Methods: We conducted a nationwide study using Korea Healthcare Bigdata. National Cancer Registry data were linked with Health Insurance Review and Assessment Service claims. Patients diagnosed with esophageal or gastric CIS between 2007 and 2019 were followed until death or December 2022. Incidence was analyzed with linear regression, survival with Kaplan–Meier methods and log-rank tests, and mortality risk with Cox proportional hazards models. Results: We identified 978 esophageal and 15,705 gastric CIS patients. Gastric CIS increased sharply (slope 212/year), while esophageal CIS rose gradually (slope 9/year). Mortality risk increased with age: patients ≥ 80 years had hazard ratios (HRs) of 5.08 (95% confidence interval [CI], 1.98–13.06) for esophageal CIS and 30.18 (95% CI, 14.17–64.26) for gastric CIS. In gastric CIS, male sex (HR 1.57; 95% CI, 1.36–1.82), squamous cell in situ (HR 3.45; 95% CI 1.29-9.26), adenocarcinoma in situ (HR 1.95; 95% CI 1.71-2.23), hypertension (HR 2.12; 95% CI 1.86-2.41), and cerebrovascular disease (HR 1.72; 95% CI 1.45-2.04) were independent mortality predictors. No comorbidities significantly predicted mortality in esophageal CIS. Body mass index and physical activity were inversely associated with gastric CIS mortality. Sex-stratified analyses showed consistent age and vascular risk effects in both sexes, while squamous histology and heart disease increased mortality only in men. Conclusions: Esophageal and gastric CIS exhibit distinct prognostic patterns.