Serum Helicobacter pylori Antibody Testing

This multicenter retrospective and prospective real-world observational study will evaluate the relationship of Helicobacter pylori (H. pylori) infection status, intragastric distribution, and pathological features with gastric cancer biological behavior and long-term prognosis in patients with early gastric cancer or related gastric neoplastic lesions undergoing endoscopic submucosal dissection (ESD). H. pylori infection is an important risk factor for gastric cancer. In clinical practice, H. pylori status can be assessed by several methods, including the 13C-urea breath test, serum H. pylori antibody testing, and pathological assessment of gastric tissue. These methods may not always provide the same result because they reflect different aspects of infection, including current active infection, previous exposure, prior eradication status, and local tissue-based detection. The study will include approximately 1500 participants from participating medical centers. About 1000 participants will be retrospectively identified from existing clinical, endoscopic, pathological, H. pylori testing, and follow-up records, and about 500 additional participants will be prospectively enrolled. The study will evaluate H. pylori infection status, prior eradication status, discordant testing patterns, tissue-based and intragastric H. pylori distribution, background mucosal changes, and pathological features of early gastric cancer or related gastric neoplastic lesions. These features will be analyzed in relation to different gastric cancer subtypes and biological behavior. Follow-up information will be used to evaluate whether the integrated analysis of H. pylori infection status and pathological features can predict clinical outcomes at 1, 2, and 3 years after ESD and during long-term follow-up, including local recurrence, metachronous gastric cancer, synchronous or multifocal early gastric cancer detected within 1 year, additional surgical treatment, survival, and other clinically meaningful outcomes.