Purpose: Due to the preservation of the entire stomach after endoscopic resection, the occurrence of metachronous gastric cancer (MGC) remains a possibility. In this study, we investigated the incidence and risk factors for MGC in patients with early gastric cancer who underwent endoscopic submucosal dissection (ESD) and successfully eradicatedHelicobacter pylori. Materials and Methods: A retrospective analysis was conducted of 1,191 patients who underwent ESD and successfully eradicated H. pylori at the Affiliated Drum Tower Hospital of Nanjing University. Endoscopic surveillance was performed at 3, 6, and 12 months post-resection, and annually thereafter. MGC was defined as the development of a new cancer at a site other than the primary gastric cancer site, at least 1 year after the initial endoscopic resection. Results: A total of 77 patients were diagnosed with MGC during a median follow-up of 41.5 months. Kaplan-Meier analysis showed a 5-year cumulative incidence of MGC of 9.4% after successful H. pylori eradication. Multivariate analysis of the training set using Cox proportional hazards models identified male sex, severe atrophic gastritis, multiple gastric cancers before H. pylori eradication, and smoking history as independent risk factors for MGC.The nomogram exhibited favorable discrimination, with area under the curves of 0.767 and 0.822 in the training set and 0.724 and 0.745 in the testing set at 3 and 5 years, respectively. Conclusions Patients with gastric cancer who undergo endoscopic resection, even after successful H. pylori eradication, should undergo annual and continuous endoscopic surveillance for MGC.

Purpose: Immune checkpoint inhibitor plus chemotherapy is the standard first-line treatment for advanced gastric cancer; however, predictive biomarkers for optimal patient selection remain unsatisfactory. This study was aimed at evaluating the predictive value of tumor mutational burden (TMB) and insertion/deletion (Indel) rate in patients with gastric cancer treated with nivolumab plus chemotherapy. Materials and Methods: This retrospective study included 132 patients with gastric cancer treated with first-line nivolumab plus chemotherapy and 185 patients treated with chemotherapy alone, all of whom had next-generation sequencing data available. The TMB and Indel cut-offs were set at 15.63 mutations per megabase and 18.19%, respectively, as determined based on their ability to best distinguish progression-free survival (PFS) among the patients who received nivolumab plus chemotherapy. Results: PFS was favorable for nivolumab and chemotherapy than for chemotherapy alone in both the high and low TMB groups; nevertheless, survival benefits were observed only in the high Indel group. Among the subgroups defined based on both TMB and Indel rates, the high TMB and high Indel rate subgroup showed the greatest benefit from nivolumab plus chemotherapy compared with that from chemotherapy alone. The benefit of this subgroup remained significant in patients with proficient mismatch repair (MMR) tumors, whose survival outcomes were comparable to those of patients with deficient MMR tumors.Among patients treated with nivolumab plus chemotherapy, high TMB and Indel rate were independently associated with favorable survival outcomes. Conclusions Thus, Indel rate, particularly in combination with TMB, may be a promising predictive biomarker for gastric cancer. However, further validation of their predictive value is warranted.

Purpose: Patient-derived cells (PDCs) and patient-derived organoids (PDOs) are complementary preclinical models widely used in translational cancer research. However, their molecular and functional differences have not been systematically characterized. This study established and analyzed paired PDC and PDO models derived from the same gastric cancer ascites to delineate platform-dependent molecular and functional profiles. Materials and Methods: Malignant ascites or pleural fluid obtained from 6 patients with advanced gastric cancer were used to establish paired PDC and PDO models. All pairs underwent comprehensive multi-omics profiling, integrating genomic, transcriptomic, and proteomic data. Phenotypic characterization included morphological, histological, proliferative, and cell cycle analyses. Drug sensitivity assays were performed using 4 chemotherapeutic agents commonly used to treat gastric cancer. Results: The 6 paired PDC and PDO models exhibited distinct morphological characteristics.Whole-genome analyses demonstrated high concordance among primary tumors, PDCs, and PDOs, confirming tumor representation across platforms. Multi-omics profiling identified platform-dependent molecular signatures; PDOs were enriched for extracellular matrix remodeling and stemness, whereas PDCs displayed proliferation- and immune-related signatures. Clinically relevant biomarkers, including HER2 and MET alterations, were concordant with primary tumors. Notably, drug responses differed between platforms and patients, indicating platform-dependent and patient-specific chemosensitivity. Conclusions Paired PDC and PDO models derived from the same patients preserved core patient-specific tumor characteristics while exhibiting distinct molecular and functional profiles. These findings underscore the culture platform as a critical determinant of experimental outcomes and therapeutic responses. Therefore, careful selection of an appropriate preclinical model is essential to accurately address biological questions and optimize precision oncology strategies.

Purpose: We identified the risk factors for remnant gastric cancer (RGC) based on remnant gastric mucosal characteristics and gastritis morphology in patients undergoing distal gastrectomy. Materials and Methods: This multicenter retrospective study included 100 patients with RGC after distal gastrectomy and 550 patients without RGC treated between 2013 and 2020.Endoscopic findings, including anastomotic redness, red streaks, enlarged folds, bile reflux as anastomotic findings, as well as disappearance of the regular arrangement of collecting venules (RAC), atrophic gastritis, and intestinal metaplasia as background gastric mucosal findings, were evaluated. Disease risk score matching (1:1) was adjusted for baseline characteristics. Logistic regression analysis was used to develop a risk score model to stratify RGC risk into low, moderate, and high categories. Results: After matching, 96 patients with RGC and 96 controls were analyzed. Anastomotic redness and red streaks, as well as the disappearance of RAC and atrophic gastritis, were significantly more frequent in the RGC group than in the control group, whereas enlarged folds and bile reflux showed no significant differences. Risk scores were assigned as follows:anastomotic redness, 2; red streaks, 3; disappearance of RAC, 7; and atrophic gastritis, 3. The total score stratified patients into high (≥15), moderate (7–14), and low risk (≤6). The positive and negative predictive values were 67.7% and 83.3%, respectively. Conclusions The endoscopic findings of anastomotic redness, red streaks, RAC disappearance, and atrophic gastritis were significantly associated with RGC development.The proposed risk-scoring model could serve as a stratification tool for RGC surveillance.

Purpose: Although gastric cancer (GC) exhibits significant genomic heterogeneity, the clinical implications of its immune microenvironment remain poorly understood. Materials and Methods: We retrospectively evaluated patients with GC who underwent gastrectomies between 2011 and 2014. The tumors were analyzed for Epstein–Barr virus (EBV), microsatellite instability-high (MSI-H), tumor-infiltrating lymphocytes (CD3), tumor-associated macrophages (CD68 and CD163), and programmed death-ligand 1 (PD-L1) expression. Tumors were classified using the modified The Cancer Genome Atlas scheme, and their clinical characteristics were compared. Results: A total of 567 patients were classified into EBV (6%), MSI-H (10%), chromosomal instability-like (36%), and genomically stable-like (48%) subtypes. EBV tumors exhibited the highest PD-L1 expression (85%) and immune infiltration by CD3+ T cells (86%), CD68+ macrophages (58%), and CD163+ macrophages (40%). High CD68+ macrophage tumors were associated with advanced stages and worse 5-year disease-free survival (83% vs. 95%; P<0.001);however, this association was not independently significant after adjusting for the tumor-nodemetastasis stage. PD-L1 expression did not significantly affect the survival outcomes. Conclusions GC subtypes have distinct immune microenvironments that influence prognosis. Our findings highlight the prognostic and therapeutic potential of immune profiling in GC.

Purpose: Endoscopic submucosal dissection (ESD) has become a standard minimally invasive treatment for selected patients with early gastric cancer (EGC). This study presents the first nationwide survey of patients with EGC treated with ESD in 2023, conducted by the Korean College of Helicobacter and Upper Gastrointestinal Research. Materials and Methods: Data were retrospectively collected from participating referral centers across Korea using a standardized case report form covering patient characteristics, tumor features, procedural details, histopathological findings, and clinical outcomes.Descriptive and comparative analyses were conducted to summarize nationwide ESD practice patterns and outcomes. Results: Data from 5,460 ESD cases from 5,250 patients across 27 institutions were analyzed. The mean age was 67.4 years, with 74.1% males. Multiple synchronous lesions were identified in 3.7%. Most lesions were located in the lower third of the stomach (64.0%), and differentiated-type adenocarcinomas accounted for 87.8%. The en bloc and complete resection rates were 99.2% and 91.4%, respectively. Curative resection was achieved in 80.5%, whereas local non-curative resection (L-NCR) and surgical non-curative resection (S-NCR) were identified in 2.8% and 16.7%, respectively. Additional surgery was performed more frequently in patients with S-NCR than in those with L-NCR (59.3% vs. 24.7%). The bleeding and perforation rates were 3.6% and 0.9%, respectively, and were mostly managed conservatively or endoscopically. The median length of hospitalization was 4.0 days. Conclusions This first nationwide survey provides a comprehensive overview of the current practice of EGC treatment using ESD in Korea, demonstrating high technical success and safety, and establishing a baseline dataset for future longitudinal research.

Although the clinical importance of esophagogastric junction (EGJ) cancer is being increasingly recognized, its definition and treatment strategies vary considerably across regions. Recently, new concepts such as the gastroesophageal junction zone have been proposed for classification of EGJ cancer. Moreover, EGJ adenocarcinoma has been shown to possess a heterogeneous molecular profile consisting of both esophageal- and gastric-like phenotypes, indicating the need for EGJ-specific therapeutic strategies.Although international clinical practice guidelines for EGJ cancer have been published, substantial regional differences remain. This review aimed to summarize recent updates on the biological characteristics and management of EGJ cancers. Trials such as TIME and MIRO have demonstrated that minimally invasive surgery (MIS) reduces postoperative complications and improves the early postoperative quality of life. More recently, the MONET trial showed that MIS is not inferior to open esophagectomy in terms of long-term oncological outcomes, and the REVATE trial demonstrated the advantages of robot-assisted surgery over thoracoscopic approaches. Perioperative treatment strategies also differ across regions. Western guidelines recommend 5-fluorouracil, leucovorin, oxaliplatin, and docetaxel (FLOT)-based perioperative chemotherapy, as supported by the FLOT4 and ESOPEC trials, whereas Asian studies, such as RESOLVE and PRODIGY, have demonstrated the efficacy of docetaxel, oxaliplatin, and S-1 or S-1 plus oxaliplatin regimens. The application of immune checkpoint inhibitors is also evolving; although KEYNOTE-585 did not show a survival advantage, the MATTERHORN trial demonstrated that durvalumab plus FLOT significantly improved event-free survival, establishing a new emerging global standard. Future directions include redefining EGJ classification, implementing molecular-guided treatment selection, advancing organ-preserving strategies, and optimizing perioperative immunochemotherapy.