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Background and study aims Laparoscopic and endoscopic cooperative surgery (LECS) for gastric submucosal tumor was developed as a type of minimal local resection and is now widely used in Asian countries. However, the oncological safety of LECS for gastric gastrointestinal stromal tumor (GIST) remains unclear. LECS has potential oncology-related problems that may influence survival outcomes. Furthermore, the feasibility and safety of LECS have not yet been fully established. Patients and methods Patients who were intended to undergo LECS for gastric GIST from 2006 to 2020 were retrospectively selected. The indication for LECS was determined according to the guidelines. The completion of LECS, complications, and survival outcomes of the patients were analyzed. Results Two hundred fifty-nine patients were eligible in this study. According to intraoperative findings, 44 patients underwent local resection without luminal endoscopic procedures. Of the remaining 215 patients, 213 completely underwent LECS, which corresponds to a completion rate of 99.1 %. Six patients (2.8 %) had postoperative complications of Clavien-Dindo classification grade II or higher. Delayed gastric emptying was most commonly found in four patients (1.9 %). Old age (P = 0.0349), female sex (P = 0.0095), tumor located in the lesser curvature (P = 0.0015), and large tumor diameter (P = 0.0232) were significantly more common in patients with complications. The 3-year overall and disease-specific survival rates were 99 % and 100 %, respectively, in 215 patients who were intended to undergo LECS. Conclusions Despite several oncological concerns, LECS for gastric GIST is oncologically safe besides a feasible and safe procedure in the short-term.

Background and study aims Management strategies for sporadic non-ampullary duodenal adenoma with low-grade dysplasia (LGD) are not well established. This study aimed to analyze progression factors and determine suitable treatment strategies for LGD lesions. Patients and methods We retrospectively analyzed consecutive LGD lesions (n = 125) in patients followed up for ≥ 6 months (median, 45 months) and evaluated the changes in clinicopathological features during follow-up. All LGD lesions were classified into two groups: stable LGD (no increase or

Background and study aims Response evaluation criteria in solid tumors (RECIST) have been the gold standard to preoperatively predict treatment response and prognosis in patients with gastric cancer (GC) after neoadjuvant chemotherapy (NAC); however, methods for patients without evaluable lesions by RECIST are not yet confirmed. The aim of this study was to assess the utility of preoperative endoscopy for predicting treatment response and prognosis in patients with GC after NAC. Patients and methods This retrospective study included 105 patients with initially resectable GC who underwent NAC followed by surgical treatment. Preoperative factors for predicting treatment response and survival outcomes were analyzed. Results The number of patients classified as responders using preoperative endoscopic assessment, RECIST, and postoperative pathological evaluation were 25 (23.8 %), 28 (26.7 %), and 18 (17.1 %), respectively. Forty-three patients (41 %) were classified as non-targeted disease only, and their treatment responses were not evaluable by RECIST. Multivariate analysis identified endoscopic response as an independent preoperative factor to predict postoperative histological treatment response (odds ratio = 4.556, 95 % CI = 1.169–17.746, P = 0.029). Endoscopic treatment response was the only independent preoperative predictive factor for overall survival (OS) (hazard ratio = 0.419, 95 % confidence interval (CI) = 0.206–0.849, P = 0.016). Further, endoscopic treatment response was available for 33 patients (76.7 %) with non-targeted disease only, which showed significantly different OS between endoscopic responders (80.0 %) and non-responders (43.5 %) (P = 0.025). Conclusions Endoscopic evaluation was an independent preoperative factor to predict treatment response and prognosis in patients with GC after NAC. Endoscopic assessment may be especially valuable for patients who could not be assessed by RECIST.

Background and study aims Colorectal endoscopic submucosal dissection (ESD) is technically challenging owing to submucosal fibrosis and difficult endoscope manipulation. Therefore, various traction methods have been reported. We often use a simple looped nylon thread attached to a clip to assist with dissection. We assessed the feasibility of mentor-guided colorectal ESD using this traction device (TD). Patients and methods From December 2017 to March 2018, we retrospectively reviewed outcomes of 101 colorectal ESDs performed by two groups of endoscopists (A, 5 endoscopists with colorectal ESD experience of 300 cases). Group A was further divided into two subgroups that performed ESD with or without TD. Results No significant difference was observed in ESD completion rates (86.1 % [62/72] vs. 96.6 % [28/29]; odds ratio [OR], 0.22; 95 % confidence interval [CI], 0.005 – 1.71; P = 0.17) or procedure times (52.0 min vs. 40.0 min; P = 0.27) and adverse event rates between groups A and B. The rate of TD use was significantly higher in group A than in group B (44.4 % [32/72] vs. 20.7 % [6/29]; OR, 3.03; CI, 1.04 – 10.23; P = 0.03). The completion rate was not different between the two subgroups of group A (with vs. without TD) (81.2 % [26/32] vs. 90.0 % [36/40]; OR, 0.49; CI, 0.09 – 2.29; P = 0.32); however, the proportion of fibrosis cases was significantly higher in the TD-use group (46.8 % [15/32] vs. 22.5 % [9/40]; OR, 2.99; CI, 0.98 – 9.59; P = 0.03). Conclusion Mentor-guided colorectal ESD using TD was performed efficiently, safely, and in a manner comparable to that of experts.

Background and study aims Delineating undifferentiated-type early gastric cancer (UD-type EGC) from noncancerous areas is difficult. Therefore, the lateral margin negative (LM−) resection rate of endoscopic submucosal dissection (ESD) is lower for UD-type EGC than for differentiated-type EGC. This study aimed to retrospectively evaluate the effectiveness of the marking methods with circumferential biopsies in ESD for UD-type EGC. Patients and methods We analyzed the clinical outcomes of ESD in 127 patients with UD-type EGC between April 2013 and 2017. We performed diagnostic delineation of cancerous areas using magnifying endoscopy with narrow-band imaging, and four or more circumferential biopsies approximately 5 mm apart from the estimated lesion border were obtained to confirm noncancerous areas. The markings were placed on the circumferential biopsy scars, and a mucosal incision line was made outside the markings. Results Median size of the tumors and ESD specimens was 12 and 35 mm, respectively. En-bloc resection rate was 100 % (127/127), and LM− and curative resection rates were 97.6 % (124/127) and 80.3 % (102/127), respectively. Circumferential biopsy in preoperative esophagogastroduodenoscopy has successfully identified the misdiagnosis of cancerous areas of four patients (3.2 %), with three (2.4%) achieving LM− resection. LM + resection was pathologically identified in three patients (2.4 %), with all undergoing non-curative resection due to > 20-mm tumor. The proportion of patients with the shortest distance ≥ 5 mm from the lesion edge to the specimen edge was 88.2 % (112/127). Conclusion Our marking methods with circumferential biopsies may reduce LM + resections in ESD for UD-type EGC.

Background and study aims Esophagogastroduodenoscopy (EGD) has utility in early detection of upper gastrointestinal (UGI) neoplasms. However, previous studies report shorter inspection times and inexperienced endoscopists contribute to overlooking gastric neoplasms. We investigated neoplasm detection rates according to inspection time and extent of EGD training. Patients and methods In this retrospective observational study, we reviewed routine EGDs for 3,925 consecutive cases between October 2014 and March 2015. We divided the endoscopists into three groups based on median inspection time during EGD without undergoing biopsy. Using cut-off median inspection times of 7 and 10 minutes, three, five, and eight endoscopists were classified into the fast, moderate, and slow groups, respectively. We compared detection rates according to inspection time and the extent of EGD training. Results The median inspection time among all endoscopists was 9.3 minutes (range, 6.6 – 12.0 min). The detection rate for UGI neoplasms was as follows: fast group, 3.6%; moderate group, 3.3 %; and slow group, 3.1 % (P = 0.807). The median inspection time was significantly shorter among the intensive training ≥ 1-year group than among the

Background and study aims Positive horizontal margins in resected specimens are sometimes encountered after endoscopic submucosal dissection (ESD) for early gastric cancers, and appropriate treatment strategies for these cases are not established. The aim of this study was to evaluate current empirical treatments for patients with positive horizontal or indeterminable margins after ESD. Patients and methods We performed a multicenter survey and data from 14 hospitals were collected. The pooled proportions of positive horizontal or indeterminable margins and those of patients followed up without early intervention were calculated using a logistic-normal random-effects model. For calculating pooled estimates, subgroup analyses of high- and non-high-volume centers were conducted. Results A total of 11,796 ESD cases were enrolled and 229 patients (2 %) had positive horizontal or indeterminable margins. Ninety-eight cases were treated within 30 days of ESD and 131 cases were followed up without early treatments. Pooled estimates of positive margins in high- and non-high-volume centers were 1 % (95 % CI: 1 % – 2 %) and 2 % (95 % CI: 1 % – 4 %), respectively, and were not heterogeneous (P = 0.191). The proportion of patients followed up without early intervention ranged from 30 % to 100 %. The pooled estimate was 68 % (95 % CI: 50 % – 83 %). The pooled estimates of high- and non-high-volume centers were 65 % (95 % CI: 38 % – 85 %) and 72 % (95 % CI: 44 % – 89 %), respectively, and were not heterogeneous (P = 0.692). Conclusion There was insufficient consensus regarding treatment strategies used for early gastric cancer with positive horizontal or indeterminable margins after ESD. Further studies are required to establish a consensus.

Background: Superficial Barrett’s esophageal adenocarcinoma (s-BEA) in Barrett’s esophagus frequently occurs in the right wall of the esophagus. Our aim was to examine the correlation between the location of s-BEA and the direction of acid and non-acid reflux in patients with Barrett’s esophagus. Patients and methods: We performed 24-h pH monitoring in 33 s-BEA patients using a pH catheter with eight sensors. One sensor was located at the 6 o’clock position in the lower esophagus and sensors 1 – 8 were arranged counterclockwise at the same level. The catheter was positioned at the same level as the s-BEA. We measured the maximal total duration of acid (MTD-A) and non-acid (MTD-NA) reflux. When the direction of MTD-A and MTD-NA coincided with the location of the s-BEA, the case was defined as coincidental and we calculated the rate of coincidence, and the probability of the rate of coincidence was estimated with 95 % confidence intervals (95 %CI). Results: Among the 33 cases of s-BEA examined, the rate of coincidence of both MTD-A and MTD-NA was 24/33 (72.7 %) (95 %CI 0.54 – 0.87). The rate of coincidence of either MTD-A or MTD-NA was 30/33 (90.9 %) (95 %CI 0.76 – 0.98). Conclusions: Our study revealed that the location of s-BEA mostly corresponds to the direction of MTD-A or MTD-NA. Accurate observation of the distribution of acid or non-acid reflux by pH monitoring would aid early detection of s-BEA by endoscopy.