Although surgery was the standard treatment for early gastrointestinal cancers, endoscopic resection is now a standard treatment for early gastrointestinal cancers without regional lymph node metastasis. High-definition white light endoscopy, chromoendoscopy, and image-enhanced endoscopy such as narrow band imaging are performed to assess the edge and depth of early gastrointestinal cancers for delineation of resection boundaries and prediction of the possibility of lymph node metastasis before the decision of endoscopic resection. Endoscopic mucosal resection and/or endoscopic submucosal dissection can be performed to remove early gastrointestinal cancers completely by en bloc fashion. Histopathological evaluation should be carefully made to investigate the presence of risk factors for lymph node metastasis such as depth of cancer invasion and lymphovascular invasion. Additional treatment such as radical surgery with regional lymphadenectomy should be considered if the endoscopically resected specimen shows risk factors for lymph node metastasis. This is the first Korean clinical practice guideline for endoscopic resection of early gastrointestinal cancer. This guideline was developed by using mainly de novo methods and encompasses endoscopic management of superficial esophageal squamous cell carcinoma, early gastric cancer, and early colorectal cancer. This guideline will be revised as new data on early gastrointestinal cancer are collected.

Background: Despite recent advances in studies on the gastric microbiome, the role of the non‐Helicobacter pylori gastric microbiome in gastric carcinogenesis remains unclear. We evaluated the characteristics of the gastric microbiome and metagenomic functions in patients with IM.Methods: Participants were classified into six groups according to disease status (chronic superficial gastritis [CSG], intestinal metaplasia [IM], and cancer) and H. pylori‐ infection status (H. pylori‐positive and H. pylori‐negative). The gastric microbiome was analyzed in mucosal tissues at the gastric antrum by 16S rRNA gene sequencing. Moreover, we assessed the metagenome including the type IV secretion system (T4SS) gene, as T4SS proteins are essential for transferring CagA from H. pylori- into the human gastric epithelium.Results: Among the 138 included patients, 48, 9, 23, 14, 12, and 32 were classified into the H. pylori‐negative CSG, H. pylori‐negative IM, H. pylori‐negative cancer, H. pylori‐positive CSG, H. pylori‐positive IM, and H. pylori‐positive cancer groups, respectively. Cyanobacteria were predominant in the H. pylori‐negative CSG group compared to in the H. pylori‐negative IM and H. pylori‐negative cancer groups (H. pylori‐negative CSG vs H. pylori‐negative IM vs H. pylori‐negative cancer: 14.0% vs 4.2% vs 0.04%, P < 0.001). In contrast, Rhizobiales were commonly observed in the H. pylori‐negative IM group (H. pylori‐negative CSG vs H. pylori‐negative IM vs H. pylori‐negative cancer: 1.9% vs 15.4% vs 2.8%, P < 0.001). The relative abundance of Rhizobiales increased as H. pylori‐infected stomachs progressed from gastritis to IM. In the H. pylori‐negative IM group, genes encoding T4SS were prevalent among the metagenome. Additionally, after H. pylori- eradication therapy, the gastric microbiome was similar to the microbiome observed after spontaneous clearance of H. pylori-.Conclusions: The relative abundance of Rhizobiales was higher in patients with H. pylori‐negative IM than in those with H. pylori‐negative CSG or cancer. Additionally, T4SS genes were highly observed in the metagenome of patients with IM. Highly abundant T4SS proteins in these patients may promote gastric carcinogenesis.

Objective: The association between proton pump inhibitor (PPI) use and gastric cancer related to Helicobacter pylori eradication has not been fully investigated in geographical regions with high risk of gastric cancer. We aimed to evaluate the association between PPIs and gastric cancer in Korea. Design: This study analysed the original and common data model versions of the Korean National Health Insurance Service database from 2002 to 2013. We compared the incidence rates of gastric cancer after 1-year drug exposure, between new users of PPIs and other drugs excluding PPIs, by Cox proportional hazards model. We also analysed the incidence of gastric cancer among PPI users after H. pylori eradication. Results: The analysis included 11 741 patients in matched PPI and non-PPI cohorts after large-scale propensity score matching. During a median follow-up of 4.3 years, PPI use was associated with a 2.37-fold increased incidence of gastric cancer (PPI≥30 days vs non-PPI; 118/51 813 person-years vs 40/49 729 person-years; HR 2.37, 95% CI 1.56 to 3.68, p=0.001). The incidence rates of gastric cancer showed an increasing trend parallel to the duration of PPI use. In H. pylori -eradicated subjects, the incidence of gastric cancer was significantly associated with PPI use over 180 days compared with the non-PPI group (PPI≥180 days vs non-PPI; 30/12 470 person-years vs 9/7814 person-years; HR 2.22, 95% CI 1.05 to 4.67, p=0.036). Conclusion: PPI use was associated with gastric cancer, regardless of H. pylori eradication status. Long-term PPIs should be used with caution in high-risk regions for gastric cancer.

Chan Hyuk Park and Sang Kil Lee. J Neurogastroenterol Motil 2020;26:171-9. https://doi.org/10.5056/jnm19240

Moon Kyung Joo, Chan Hyuk Park, Joon Sung Kim, Jae Myung Park, Ji Yong Ahn, Bong Eun Lee, Jeong Hoon Lee, Hyo-Joon Yang, Yu Kyung Cho, Chang Seok Bang, Beom Jin Kim, Hye-Kyung Jung, Byung-Wook Kim, and Yong Chan Lee, Korean College of Helicobacter and Upper Gastrointestinal Research. Gut and Liver 2020;14:707-26. https://doi.org/10.5009/gnl20246