Supplemental Material for: Factors associated with all-cause mortality in Gastroesophageal Carcinoma in Situ: Nationwide Cohort Study

Incidence was analyzed with linear regression, survival with Kaplan–Meier methods and log-rank tests, and mortality risk with Cox proportional hazards models.</p><p dir="ltr">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.</p><p dir="ltr">Conclusions: Esophageal and gastric CIS exhibit distinct clinical and all-cause mortality patterns, largely reflecting age and comorbidity burden rather than progression of the pre-invasive lesion itself. </p>