Adenocarcinoma of the Esophagogastric Junction

This two-center retrospective observational cohort study compares Chinese and Russian patients who underwent curative proximal gastrectomy with double-tract reconstruction for proximal gastric adenocarcinoma or Siewert type II/III adenocarcinoma of the esophagogastric junction. The study evaluates postoperative reflux, nutritional status, perioperative outcomes, complications, and long-term survival. Propensity score matching will be used to improve comparability between the two cohorts.

The goal of this clinical trial is to learn if the EndoScell Scanner (ES) imaging system can accurately assess tumor-free surgical margins during surgery for adenocarcinoma of the esophagogastric junction (AEG), compared with standard frozen-section pathology. The main questions it aims to answer are: * Is ES non-inferior to intraoperative frozen-section pathology in identifying positive or negative tumor margins? * Does ES shorten the time needed for margin assessment and reduce the number of additional tissue resections required? Researchers will compare an ES-assisted surgical arm with a conventional frozen-section arm to see if ES improves margin accuracy, shortens operative time, and increases the rate of complete (R0) tumor removal. Participants will * undergo standard AEG resection with randomized assignment to either ES or frozen-section margin checks; * allow collection of margin tissue samples for ES, frozen-section, and final paraffin pathology; * attend routine follow-up visits for up to 2 years to monitor for local recurrence.