Impact of prior cancer history on survival in patients with adenocarcinoma of esophagogastric junction: a retrospective cohort study using SEER database.

Background: The exclusion of patients with prior malignancies from clinical trials remains controversial, yet its prognostic impact on adenocarcinoma of esophagogastric junction (AEG) is poorly characterized. This retrospective cohort study aimed to evaluate the prevalence and survival implications of prior cancer in AEG patients, providing evidence for refining trial eligibility criteria. Methods: The Surveillance, Epidemiology, and End Results databases were used to collect data between 1975 and 2021, and 10,895 AEG patients were included in the study. Inclusion required histologically confirmed AEG with complete follow-up data and only those with one prior cancer preceding the index AEG diagnosis to ensure temporal clarity. Prior cancers were classified according to their primary site, frequency, stage, and timing. Survival analyses included Kaplan-Meier curves, multivariate Cox regression, and competing risk models (Fine and Gray's). Propensity score matching was applied as a sensitivity analysis to validate the robustness of the primary findings. Results: Among 10,895 eligible patients, 16.58% (n=1,806) had prior cancer history and a median age of 67 years, with 79.20% male patients. The cohort showed significantly different overall survival (median 13 months for prior cancer Conclusions: While prior cancer history adversely impacts overall survival in AEG patients, specific subgroups-particularly those with select cancer types-exhibit comparable outcomes. These findings suggest that current exclusion criteria may be overly restrictive, and support refining trial eligibility to include well-selected prior-cancer patients.