Background: In the treatment of early gastric cancer, patients suitable for endoscopic submucosal dissection (ESD) are selected on the basis of endoscopic findings and biopsy results, while the final diagnosis is confirmed by examination of the resected specimen. Aim: To examine the discrepancies between clinical and pathological findings before and after ESD. Materials and Methods: We retrospectively identified 335 lesions treated by ESD for early gastric cancer at the National Cancer Center between 2020 and 2025, compared the endoscopic, biopsy and pathological findings, and identified the factors associated with discrepancy. Result: At least one of the three pre-treatment parameters was discordant in 175 lesions (52.2%). Of the 249 lesions judged to be ulcer-free on endoscopy, 51 (20.5%) were ulcerated histologically, while 28 lesions were overestimated (P<0.05). Underestimation of ulceration was more likely in lesions located in the upper or middle third of the stomach (OR 2.17, 95% CI 1.22–3.99) and in lesions measuring ≥20 mm (OR 1.68, 95% CI 1.00–2.84). Of the 110 lesions diagnosed as high-grade dysplasia on biopsy, 36 (32.7%) contained adenocarcinoma in the resected specimen, one of which was of undifferentiated type. Of the remaining 18 undifferentiated lesions, 6 (33.3%) had been diagnosed as differentiated type before treatment. Submucosal and lymphovascular invasion were associated with a tumor size of ≥20 mm (OR 3.58 and 3.15) and undifferentiated histology (OR 4.47 and 7.56); all P<0.01. Conclusion A significant discrepancy was observed between the pre- and post-ESD clinicopathological findings.

Background: A 2024 study by the National Statistical Office of Mongolia indicate an incidence rate of 38.8 per 100 000 population, with a total of 8169 new cancer cases diagnosed, of which 16.2% are gastric cancers. Notably, 64.4% of these diagnoses are made at advanced stages.2 Surgical intervention remains one of the most effective treatments for gastric cancer. Early-stage surgery confers a 5-year survival rate of 60-80%, whereas late-stage diagnosis reduces this to 18-50%.5 This study aims to investigate the causes, types, and contributing factors of postgastrectomy anemia in patients undergoing surgery for gastric cancer in Mongolia, where no prior study has been conducted on this topic. Methods: This retrospective study analyzed all patients who underwent gastric cancer surgery at the National Cancer Center of Mongolia from 2022 to 2024. Data on demographics, lifestyle factors, clinical signs of anemia, and comorbidities were collected from medical records and confirmed by direct examination. Results: A total of 788 patients who underwent surgery for gastric cancer were included in the study, of whom 70.5% were male and 29.5% female, aged 22–70 years (mean age 46 years). Among the total cases, 461 patients underwent total gastrectomy, 128 had distal gastrectomy with gastrojejunal anastomosis, 39 underwent partial gastrectomy, 3 had gastrectomy with duodenal anastomosis, 5 underwent gastrectomy with esophagogastric anastomosis, and 6 underwent bypass procedures. Conclusions Postoperative monitoring after gastric surgery was insufficient, and there was a tendency for anemia to progress.