A survey of current practices in post-polypectomy surveillance in Korea.

BACKGROUND/AIMS: We investigated the clinical practice patterns of post-polypectomy colonoscopic surveillance among Korean endoscopists. METHODS: In a web-based survey conducted between September and November 2021, participants were asked about their preferred surveillance intervals and the patient age at which surveillance was discontinued. Adherence to the recent guidelines of the U.S. Multi-Society Task Force on Colorectal Cancer (USMSTF) was also analyzed. RESULTS: In total, 196 endoscopists completed the survey. The most preferred first surveillance intervals were: a 5-year interval after the removal of 1-2 tubular adenomas < 10 mm; a 3-year interval after the removal of 3-10 tubular adenomas < 10 mm, adenomas ≥ 10 mm, tubulovillous or villous adenomas, ≤ 20 hyperplastic polyps < 10 mm, 1-4 sessile serrated lesions (SSLs) < 10 mm, hyperplastic polyps or SSLs ≥ 10 mm, and traditional serrated adenomas; and a 1-year interval after the removal of adenomas with highgrade dysplasia, >10 adenomas, 5-10 SSLs, and SSLs with dysplasia. In piecemeal resections of large polyps ( > 20 mm), surveillance colonoscopy was mostly preferred after 1 year for adenomas and 6 months for SSLs. The mean USMSTF guideline adherence rate was 30.7%. The largest proportion of respondents (40.8%-55.1%) discontinued the surveillance at the patient age of 80-84 years. CONCLUSIONS: A significant discrepancy was observed between the preferred post-polypectomy surveillance intervals and recent international guidelines. Individualized measures are required to increase adherence to the guidelines.

Exploring microRNA patterns as biomarkers of FOLFOX chemotherapy-induced peripheral neuropathy in patients with colorectal cancer.

FOLFOX is a combination of chemotherapeutic agents (5-fluorouracil, leucovorin, and oxaliplatin) and is used to treat advanced colorectal cancer (CRC) but induces various side effects. Chemotherapy-induced peripheral neuropathy (CIPN) is one of the most critical side effects that compromise the quality of life of patients with CRC undergoing FOLFOX chemotherapy. This study aimed to evaluate circulating miRNA, cortisol and catecholamine as potential biomarkers that can predict FOLFOX-CIPN symptoms. High-throughput microRNA (miRNA) sequencing was performed on the RNA circulating in the plasma of eight patients with CRC who underwent FOLFOX chemotherapy. miRNA expression profiles were evaluated according to two groups: those who underwent ≤3 cycles and those who underwent ≥6 cycles of FOLFOX chemotherapy. The identified miRNAs were validated in 27 patients with CRC who underwent FOLFOX chemotherapy using quantitative reverse transcription polymerase chain reaction. Target genes were predicted using bioinformatics and functional analyses. Cortisol and catecholamine concentrations in peripheral plasma were measured using an enzyme-linked immunosorbent assay. miR-3184-5p was differentially expressed when miRNA expression was compared between the groups that underwent ≤3 and ≥6 cycles of FOLFOX chemotherapy. Cortisol levels were significantly higher in the group that underwent ≥6 cycles of FOLFOX chemotherapy than in the group that underwent ≤3 cycles. This study suggests that miR-3184-5p may be a potential marker for predicting CIPN.

Endoscopic mucosal resection using anchored snare Tip-in versus precut technique for small rectal neuroendocrine tumors.

BACKGROUND/AIMS: Small rectal neuroendocrine tumors (NETs) can be treated with modified endoscopic mucosal resection (EMR). However, an optimal EMR method remains to be established. We aimed to assess the non-inferiority of Tip-in EMR versus precut EMR (EMR-P) for treating rectal NETs. METHODS: This prospective, multicenter, randomized controlled trial enrolled patients with rectal NETs of < 10 mm in diameter. The patients were randomly assigned to EMR-P and Tip-in EMR groups in a 1:1 ratio. Primary outcome was margin-negative (R0) resection rate between the two methods, with a noninferiority margin of 10%. RESULTS: Seventy-five NETs in 73 patients, including 64 eligible lesions (32 lesions in each, EMR-P and Tip-in EMR groups), were evaluated. In a modified intention-to-treat analysis, R0 resection rates of the EMR-P and Tip-in EMR groups were 96.9% and 90.6%, respectively, which did not demonstrate non-inferiority (risk difference, -6.3 [95% confidence interval: -18.0 to 5.5]). Resection time in the EMR-P group was longer than that in the Tip-in EMR group (p < 0.001). One case of intraprocedural bleeding was reported in each group. CONCLUSION: We did not demonstrate the non-inferiority of Tip-in EMR compared to EMR-P for treating small rectal NETs. However, the R0 resection rates for both techniques were high enough for clinical application.

A Gastric Magnetic Foreign Body Incidentally Detected Several Years after Ingestion.

Foreign body ingestion is commonly seen in children. However, occasionally it may also be seen among adults and is often associated with intellectual disability, psychiatric disorders, and alcoholism. Ingestion of a magnetic foreign body may cause complications such as gastrointestinal tract perforation, wherein emergency endoscopic removal of the foreign body is generally required. Here, we report a rare case of a 59-year-old male with an intellectual disability and psychiatric disorder in whom metallic objects in the stomach cavity were accidentally discovered during abdominal CT. Esophagogastroduodenoscopy revealed several metallic objects attached to two magnets, which had been ingested several years before and had remained in the stomach cavity. The magnets and metallic objects were safely removed endoscopically using rat-tooth forceps without complications.

Patient-derived Organoid Model for Predicting the Chemoresponse in Patients With Colorectal Cancer.

BACKGROUND/AIM: Cancer mortality has decreased due to the contribution of extensive research on cancer treatment, including chemotherapy, radiation, and immunotherapy. However, histopathologically similar tumors originating from the same organ are treated with identical or similar chemotherapeutic regimens regardless of patient characteristics or cancer subtypes. The aim of this study was to evaluate the utility of organoids in predicting responses to chemotherapeutic agents. PATIENTS AND METHODS: This study retrospectively reviewed patient-derived organoids (PDOs) from 10 colorectal cancer patients to compare chemotherapy responses. Drug sensitivities for 5-fluorouracil (5-FU), cisplatin, oxaliplatin, and irinotecan were compared using GI50 (concentration that inhibits cancer cell growth by 50%). RESULTS: When organoids were treated with 5-FU, GI50 was the lowest compared to the other three chemotherapeutic agents (cisplatin, oxaliplatin, and irinotecan). The responsiveness to chemotherapeutic agents differed depending on specific patient characteristics including age, tumor location, stage, and gross type. The response of the patients' organoids to chemotherapeutic agents was consistent with the response to chemotherapy actually performed in those patients with cancer recurrence after surgery. CONCLUSION: PDOs may be useful as a preclinical model in predicting chemotherapy responses in cancer patients.

Feasibility of endoscopic resection and impact of endoscopic ultrasound-based surveillance on colorectal subepithelial tumors.

BACKGROUND: Owing to the rising number of screening endoscopies and instrumental advances in endoscopic ultrasound (EUS), colorectal subepithelial tumors (SETs) are being increasingly detected. We aimed to determine the feasibility of endoscopic resection (ER) and the impact of EUS-based surveillance on colorectal SETs. METHODS: The medical records of 984 patients with incidentally detected colorectal SETs between 2010 and 2019 were retrospectively reviewed. Overall, 577 colorectal SETs underwent ER, and 71 colorectal SETs underwent serial colonoscopy for > 12 months. RESULTS: The mean tumor size (± standard deviation) of 577 colorectal SETs for which ER was performed was 7.0 ± 5.7 (median, 55; range, 1-50) mm; 475 tumors were located in the rectum and 102, in the colon. En bloc resection was achieved in 560/577 treated lesions (97.1%), and complete resection was achieved in 516/577 (89.4%). ER-related adverse events occurred in 15/577 (2.6%) patients. SETs originating from the muscularis propria showed a higher risk of ER-related adverse events and perforation than SETs arising from the mucosal or submucosal layer (odds ratio [OR] 19.786, 95% confidence interval [CI] 4.556-85.919; P = 0.002 and OR 141.250, 95% CI 11.596-1720.492; P = 0.046, respectively). Seventy-one patients were followed up after EUS without any treatment for > 12 months, during which three showed progression; eight, regression; and sixty, no changes. CONCLUSIONS: ER for colorectal SETs showed excellent efficacy and safety. Additionally, colorectal SETs without high-risk features in surveillance with colonoscopy showed an excellent prognosis.

Incidence and adverse clinical events of primary sclerosing cholangitis with ulcerative colitis.

PURPOSE: The aim of this study was to conduct a nationwide population-based study to estimate the incidence of primary sclerosing cholangitis in patients with ulcerative colitis (UC-PSC) and investigate healthcare use, medication use, surgery, cancer, and death as adverse clinical events of UC-PSC. METHODS: We identified incident cases of UC with (UC-PSC) or without PSC (UC-alone) between 2008 and 2018 using health insurance claims data in Korea. Univariate (crude hazard ratio (HR)) and multivariate analyses were performed to compare the risk of adverse clinical events between groups. RESULTS: A total of 14,406 patients with UC using population-based claims data were detected in the cohort. Overall, 3.38% (487/14,406) of patients developed UC-PSC. During a mean follow-up duration of approximately 5.92 years, the incidence of PSC in patients with UC was 185 per 100,000 person-years. The UC-PSC group showed statistically more frequent healthcare use (hospitalization and emergency department visits: HRs, 5.986 and 9.302, respectively; P < .001), higher immunomodulator and biologic use (azathioprine, infliximab, and adalimumab: HRs, 2.061, 3.457, and 3.170, respectively; P < .001), and higher surgery rate (operation for intestinal obstruction, and colectomy: HRs, 9.728 and 2.940, respectively; P < .001) than did the UC-alone group. The UC-PSC group also showed significantly higher colorectal cancer and biliary tract cancer (HRs, 2.799 and 36.343, respectively; P < .001) and mortality (HR, 4.257) rates than did the UC-alone group. CONCLUSION: Patients with UC-PSC have higher risks of colorectal cancer, biliary tract cancer, and death than do patients with UC-alone. Although considered a rare disease, managing this complex and costly disease requires recognition of the impact of increased burden on healthcare services.

Longitudinal trends in direct costs and healthcare utilization ascribable to inflammatory bowel disease in the biologic era: a nationwide, population-based study.

BACKGROUND AND AIM: Biologic-era data regarding the direct cost and healthcare utilization of inflammatory bowel disease at the population level are limited, especially in Asia. Thus, we aimed to investigate the nationwide prevalence, direct cost, and healthcare utilization of inflammatory bowel disease in Korea in a recent 10-year period. METHODS: Using the Korean National Health Insurance claim data from 2008 to 2017, we investigated all prescription medications and their associated direct costs, hospitalizations, and outpatient visits. We also estimated the nationwide prevalence of inflammatory bowel disease using population census data. RESULTS: The estimated inflammatory bowel disease prevalence significantly increased from 108.8/100 000 in 2008 to 140.4/100 000 in 2017. The overall annual costs for inflammatory bowel disease and the healthcare cost per capita increased from $24.5 million (in US dollars) to $105.1 million and from $458.4 to $1456.6 million, respectively (both P < 0.001). Whereas the ratio of outpatient costs increased from 35.3% to 69.4%, that of outpatient days remained steady. The total annual medication cost and proportion rose from $13.3 million to $76.8 million and from 54.2% to 73.3%, respectively, mainly due to the increasing antitumor necrosis factor cost, from $1.5 million to $49.3 million (from 11.1% to 64.1% of the total annual drug cost and from 6.3% to 46.9% of the total annual cost). CONCLUSIONS: We observed increasing trends in the prevalence, direct costs, and healthcare utilization of inflammatory bowel disease in Korea in recent years. The attributable cost was mainly driven by rising expenditures on antitumor necrosis factor medications.

A Review of Colonoscopy in Intestinal Diseases.

Since the development of the fiberoptic colonoscope in the late 1960s, colonoscopy has been a useful tool to diagnose and treat various intestinal diseases. This article reviews the clinical use of colonoscopy for various intestinal diseases based on present and future perspectives. Intestinal diseases include infectious diseases, inflammatory bowel disease (IBD), neoplasms, functional bowel disorders, and others. In cases of infectious diseases, colonoscopy is helpful in making the differential diagnosis, revealing endoscopic gross findings, and obtaining the specimens for pathology. Additionally, colonoscopy provides clues for distinguishing between infectious disease and IBD, and aids in the post-treatment monitoring of IBD. Colonoscopy is essential for the diagnosis of neoplasms that are diagnosed through only pathological confirmation. At present, malignant tumors are commonly being treated using endoscopy because of the advancement of endoscopic resection procedures. Moreover, the characteristics of tumors can be described in more detail by image-enhanced endoscopy and magnifying endoscopy. Colonoscopy can be helpful for the endoscopic decompression of colonic volvulus in large bowel obstruction, balloon dilatation as a treatment for benign stricture, and colon stenting as a treatment for malignant obstruction. In the diagnosis of functional bowel disorder, colonoscopy is used to investigate other organic causes of the symptom.

The effect of biological agent on body composition in patients with Crohn's disease.

BACKGROUND: Crohn's disease (CD) is associated with altered body composition, affecting clinical outcomes. We evaluated the impact of biologics on body composition in CD patients. METHODS: This multicenter longitudinal study across four Korean university hospitals conducted from January 2009 to August 2021 retrospectively reviewed data of CD patients with abdominal computed tomography (CT) before and after the biologic treatment. Skeletal muscle area (SMA), visceral fat area (VFA), and subcutaneous fat area (SFA) of the third lumbar vertebra (L3) on CT were measured. Myopenia was defined as L3 skeletal muscle index (SMI) of < 49 and < 31 cm2/m2 for men and women, respectively. RESULTS: Among 112 participants, 79 (70.5%) had myopenia. In the myopenia group, all body composition parameters were significantly increased after the biologic treatment: SMI (37.68 vs. 39.40 cm2/m2; P < 0.001), VFA (26.12 vs. 54.61 cm2; P < 0.001), SFA (44.29 vs. 82.42 cm2; P < 0.001), while no significant differences were observed in the non-myopenia group. In multivariate analysis, penetrating CD (hazard ratio, 5.40; P = 0.020) was the independent prognostic factor for surgery. Operation-free survival rate tended to decrease in the myopenia group (Log-rank test, P = 0.090). CONCLUSIONS: Biological agents can increase all body composition parameters in CD patients with myopenia. These patients are more likely to experience surgery.

Clinical outcomes and risk factors associated with poor prognosis after endoscopic resection of 10-20 mm rectal neuroendocrine tumors: a multicenter, retrospective study of 10-year experience.

BACKGROUND: The efficacy of endoscopic resection for of 10-20 mm rectal neuroendocrine tumor (NET) remains controversial. We aimed to evaluate the clinical outcomes and risk factors associated with poor prognosis after endoscopic resection of 10-20 mm rectal NET and to determine the optimal treatment. METHODS: Patients who underwent endoscopic resection for rectal NET in four tertiary hospitals were enrolled, and data on with the clinical outcomes and risk factors related to poor prognosis were retrospectively analyzed. RESULTS: A total of 105 patients who underwent endoscopic submucosal resection (ESD; n = 65, 61.9%), modified endoscopic mucosal resection (mEMR; n = 31, 29.5%), and conventional EMR (cEMR; n = 9, 8.6%) were enrolled. The mean follow-up period was 41.2 ± 21.9 months. In the morphologic findings, the mean diameter was 11.6 mm (range 10-19); the shape was sessile (50.5%) and mixed type (49.5%), and surface depression was observed in 41.9% of patients. In the histologic findings, 87.6% of patients had G1 and 12.4% G2 tumor grade, and 3.8% of patients had lymphovascular invasion. The overall en bloc and histologically complete (R0) resections were 99.1% and 76.2%, respectively. cEMR was a less-frequently developed R0 resection. In the univariate and multivariate analyses for R0 resection, only surface depression was significantly associated. Regional or distant organs metastasis during follow-up developed in three patients (2.9%) and was significantly associated with female sex, redness, G2 tumor grade, and non-ESD methods. CONCLUSION: Patients who underwent endoscopic resection of 10-20 mm rectal NET had good prognosis; therefore, endoscopic resection can be considered as the first-line treatment, particularly for 10-14 mm rectal NET. However, the risk factors, such as female sex, redness, G2 tumor grade and non-ESD methods, were associated with regional or distant metastases during follow-up. Therefore, patients with these risk factors should be carefully monitored.

Korean Guidelines for Postpolypectomy Colonoscopic Surveillance: 2022 revised edition.

Colonoscopic polypectomy is effective in decreasing the incidence and mortality of colorectal cancer (CRC). Premalignant polyps discovered during colonoscopy are associated with the risk of metachronous advanced neoplasia. Postpolypectomy surveillance is the most important method for managing advanced metachronous neoplasia. A more efficient and evidence-based guideline for postpolypectomy surveillance is required because of the limited medical resources and concerns regarding colonoscopy complications. In these consensus guidelines, an analytic approach was used to address all reliable evidence to interpret the predictors of CRC or advanced neoplasia during surveillance colonoscopy. The key recommendations state that the high-risk findings for metachronous CRC following polypectomy are as follows: adenoma ≥10 mm in size; 3 to 5 (or more) adenomas; tubulovillous or villous adenoma; adenoma containing high-grade dysplasia; traditional serrated adenoma; sessile serrated lesion containing any grade of dysplasia; serrated polyp of at least 10 mm in size; and 3 to 5 (or more) sessile serrated lesions. More studies are needed to fully comprehend the patients who are most likely to benefit from surveillance colonoscopy and the ideal surveillance interval to prevent metachronous CRC.

Outcomes according to treatment modalities as a bridge to curative surgery for malignant obstruction of the proximal colon: stent versus stoma.

BACKGROUND/AIMS: The optimal treatment for acute malignant obstruction of the proximal colon (MOPC, proximal to the splenic flexure) remains challenging. Emergency resection, the traditional modality for MOPC, has shown significantly high mortality and morbidity rates, according to recent studies. This study aimed to investigate the clinical outcomes of stent vs stoma as a bridge to curative surgery for MOPC. METHODS: This retrospective cohort study included 72 patients who underwent endoscopic placement of a self-expanding metallic stent (SEMS) or loop ileostomy for MOPC at six referral centers between January 2011 and July 2021. Clinical and pathological characteristics, procedure-related complications, and long-term mortality rates after curative surgery were analyzed. RESULTS: During a mean follow-up period of 32 months, 30 patients (41.7%) underwent ileostomy preferentially for more proximal cancer, complete obstruction, and advanced tumor stage compared to the SEMS group. No difference was found in procedure-related complications, but five deaths were observed after ileostomy. Survival analysis for 5-year mortality after curative surgery showed no significant difference between the bridge modalities (log-rank p = 0.253). CONCLUSION: In this study, SEMS as a bridge to surgery showed relatively safe results in terms of post-procedural mortality. However, these results should be considered when performing ileostomy in patients with more advanced malignant obstruction.

Korean guidelines for postpolypectomy colonoscopic surveillance: 2022 revised edition.

Colonoscopic polypectomy is effective in decreasing the incidence and mortality of colorectal cancer (CRC). Premalignant polyps discovered during colonoscopy are associated with the risk of metachronous advanced neoplasia. Postpolypectomy surveillance is the most important method for the management of advanced metachronous neoplasia. A more efficient and evidence-based guideline for postpolypectomy surveillance is required because of limited medical resources and concerns regarding colonoscopy complications. In these consensus guidelines, an analytic approach was used to address all reliable evidence to interpret the predictors of CRC or advanced neoplasia during surveillance colonoscopy. The key recommendations state that the high-risk findings for metachronous CRC following polypectomy are as follows: (1) adenoma ≥10 mm in size; (2) 3 to 5 (or more) adenomas; (3) tubulovillous or villous adenoma; (4) adenoma containing high-grade dysplasia; (5) traditional serrated adenoma; (6) sessile serrated lesion (SSL) containing any grade of dysplasia; (7) serrated polyp of at least 10 mm in size; and (8) 3 to 5 (or more) SSLs. More studies are needed to fully comprehend the patients most likely to benefit from surveillance colonoscopy and the ideal surveillance interval to prevent metachronous CRC.

[Korean Guidelines for Postpolypectomy Colonoscopic Surveillance: 2022 Revised Edition].

Colonoscopic polypectomy is effective in decreasing the incidence and mortality of colorectal cancer (CRC). Premalignant polyps discovered during colonoscopy are associated with the risk of metachronous advanced neoplasia. Postpolypectomy surveillance is the most important method for managing advanced metachronous neoplasia. A more efficient and evidence-based guideline for postpolypectomy surveillance is required because of the limited medical resources and concerns regarding colonoscopy complications. In these consensus guidelines, an analytic approach was used to address all reliable evidence to interpret the predictors of CRC or advanced neoplasia during surveillance colonoscopy. The key recommendations state that the high-risk findings for metachronous CRC following polypectomy are as follows: 1) adenoma ≥10 mm in size; 2) 3-5 (or more) adenomas; 3) tubulovillous or villous adenoma; 4) adenoma containing high-grade dysplasia; 5) traditional serrated adenoma; 6) sessile serrated lesion (SSL) containing any grade of dysplasia; 7) serrated polyp of at least 10 mm in size; and 8) 3-5 (or more) SSLs. More studies are needed to fully comprehend the patients who are most likely to benefit from surveillance colonoscopy and the ideal surveillance interval to prevent metachronous CRC.

Long-term prognosis of curative endoscopic submucosal dissection for early colorectal cancer according to submucosal invasion: a multicenter cohort study.

BACKGROUND: Endoscopic submucosal dissection (ESD) can provide a high en bloc resection rate and has been widely applied as curative treatment for early colorectal cancer (ECC). However, surgical treatment is occasionally required, and reports on the long-term prognosis of ESD are insufficient. This study aimed to investigate the long-term outcomes of ECC removal by ESD, including local recurrence and metastasis. METHODS: This multicenter study was conducted retrospectively on 450 consecutive patients with ECC who were treated with ESD between November 2003 and December 2013. Clinical, pathological, and endoscopic data were collected to determine tumor depth, resection margin, lymphovascular invasion, and recurrence. RESULTS: The median follow-up period was 53.8 (12-138 months). The en bloc resection rate was 85.3% (384) and in intramucosal cancer being 84.1% and in superficial submucosal invasion (SM1) cancer being 89.8% (p = 0.158). The curative resection rate was 76.0% (n = 342), and there was no statistical difference between the two groups (77.3% vs. 71.4%, p = 0.231). The overall recurrence free survival rate (RFS) was 98.7% (444/450). In patients with curative resection, there was no statistically significant difference in RFS according to invasion depth (intramucosal: 99.3% vs. SM1: 97.1%, p = 0.248). CONCLUSIONS: Patients with curatively resected ECC treated with ESD showed favorable long-term outcomes. Curatively resected SM1 cancer has a RFS similar to that of intramucosal cancer.

Endoscopic treatment for rectal neuroendocrine tumor: which method is better?

Recently, research on rectal neuroendocrine tumors (NETs) has increased during the last few decades. Rectal NETs measuring <10 mm without atypical features and confined to the submucosal layer have only 1% risk of metastasis, and the long-term survival probability of patients without metastasis at the time of diagnosis is approximately 100%. Therefore, the current guidelines suggest endoscopic resection of rectal NETs of <10 mm is regarded as a safe therapeutic option. However, there are currently no clear recommendations for technique selection for endoscopic resection. The choice of treatment modality for rectal NETs should be based on the lesion size, endoscopic characteristics, grade of differentiation, depth of vertical involvement, lymphovascular invasion, and risk of metastasis. Moreover, the complete resection rate, complications, and experience at the center should be considered. Modified endoscopic mucosal resection is the most suitable resection method for rectal NETs of <10 mm, because it is an effective and safe technique that is relatively simple and less time-consuming compared with endoscopic submucosal dissection. Endoscopic submucosal dissection should be considered when the tumor size is >10 mm, suctioning is not possible due to fibrosis in the lesion, or when the snaring for modified endoscopic mucosal resection does not work well.

Diagnostic performance of endoscopic ultrasonography-guided fine-needle biopsy in upper gastrointestinal subepithelial tumors measuring 2-5 cm in size.

BACKGROUND: Subepithelial tumors (SETs) in the upper gastrointestinal (GI) tract are frequently discovered during upper endoscopy, and their management is determined based on size and histopathological diagnosis. We aimed to evaluate the diagnostic performance of endoscopic ultrasonography-guided fine-needle biopsy (EUS-FNB) in upper GI SETs of 2-5 cm in size. METHODS: We included 63 patients who underwent EUS-FNB for upper GI SETs of 2-5 cm in size between January 2013 and February 2020. The diagnostic yield of EUS-FNB, ability of EUS-FNB in discriminating malignant from non-malignant lesions, and histopathological concordance between EUS-FNB specimens and resected specimens were evaluated. RESULTS: Successful acquisition of macroscopic tissue cores was possible in all 63 cases, and the diagnostic yield of EUS-FNB was 92.1% (58/63). The sensitivity, specificity, and accuracy of EUS-FNB in discriminating malignant from non-malignant lesions were 100% (95% confidence interval [CI] 85.3-100%), 87.8% (95% CI 79.9-87.8%), and 92.1% (95% CI 81.8-92.1%), respectively. Of the 26 SETs that were endoscopically or surgically resected after EUS-FNB, the histopathological concordance rate between the EUS-FNB specimens and resected specimens was 100% (24/24), except in two cases of inadequate results with EUS-FNB specimens. CONCLUSION: EUS-FNB provides high diagnostic yield and high capability in discriminating malignant from non-malignant lesions in upper GI SETs of 2-5 cm in size.