Abstract 4794: Impact of prior upper endoscopy on gastric cancer stage and survival

Abstract Background: While gastric cancer (GC) incidence in the US has decreased, 5-year survival remains at 34.5%. Early diagnosis offers curative or treatable options, yet many cases are detected at an advanced stage with poor prognosis. In high-incidence East Asian countries with established screening programs, endoscopic screening demonstrates stage shift towards early GC diagnosis and reduced GC-related mortality. Analyses of these programs have reported benefit of endoscopic screening up to 36 months prior to diagnosis. This study explores the impact of esophagogastroduodenoscopy (EGD) in this timeframe on GC stage at diagnosis and survival in an older US population. Methods: The SEER-Medicare database was queried from 2000 to 2017 for patients 68 years of age or older with histologically confirmed GC with continuous Medicare enrollment for at least 36 months prior to GC diagnosis. We excluded patients with prior cancer history and those diagnosed by autopsy or death certificate. Medicare claims files were searched for EGD claims 6-36 months prior to GC diagnosis. We excluded claims in the 6 months prior to diagnosis to avoid capturing potential diagnostic EGD. We defined the exposed group as patients with an EGD claim 6-36 months prior to GC diagnosis (Prior EGD) and the unexposed group as patients with no EGD claim in this period (No Prior EGD). Propensity score analysis balanced baseline differences for patients with and without Prior EGD using covariates sex, age and year of diagnosis, race and ethnicity, rural/urban, comorbidity, SES, and marital status. The primary outcome was in situ/local-stage GC (early) at diagnosis compared to regional/distant-stage (advanced). Secondary outcomes were 5-year overall and GC-specific survival. The adjusted odds of having in situ/local-stage GC diagnosis compared to regional/distant-stage was estimated using logistic regression, and survival analysis was done using the Kaplan-Meier method. Results: In 10,572 patients with GC (57.5% male, mean age 78.8 years), 16.4% had Prior EGD (n=1,736). Patients with Prior EGD had a significantly higher proportion of GC diagnosed in local stage compared to patients with No Prior EGD (45.7% vs. 30.2%, p < 0.001). After controlling for confounders, Prior EGD group had two-fold increased odds of GC diagnosis at early-stage compared with No Prior EGD (OR=1.99, 95% CI: 1.88-2.10). Compared with No Prior EGD, Prior EGD was associated with higher overall survival (5-year survival 32.1% vs. 22.7%, p<0.001) and GC-specific survival (5-year survival 46.0% vs. 31.1%, p<0.001), both driven by early-stage disease. Conclusions: Our analysis demonstrates that EGD up to 36 months prior to the diagnosis of GC is associated with earlier stage at diagnosis and improved overall and GC-specific survival. This study of an older population suggests that endoscopic screening may be beneficial even in a low-incidence country such as the US and warrants further study. Citation Format: Sophie Wagner, Jennifer S. Ferris, Josephine Soddano, Ji Yoon Yoon, Sheila D. Rustgi, Haley Zylberberg, Jeong Yun Yang, Yongmei Huang, Ling Chen, Chin Hur. Impact of prior upper endoscopy on gastric cancer stage and survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4794.