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Objectives A single‐balloon overtube (SBO) can improve poor scope operability during colonic endoscopic submucosal dissection (ESD). We aimed to evaluate the clinical usefulness of SBO for ESD in the proximal colon and the predictive factors for cases in which SBO is useful. Methods A total of 88 tumors located in the proximal colon resected by balloon‐assisted ESD (BA‐ESD) using SBO and 461 tumors resected by conventional ESD (C‐ESD) between June 2015 and November 2020 were considered. Seventy‐eight tumors each in the BA‐ESD and C‐ESD groups were matched by propensity score matching. ESD outcomes were compared between the groups, and a decision tree analysis was performed to explore the predictive factors for cases in which SBO is useful. Results There were no significant differences between the groups in the major outcomes such as en bloc resection rate (95% vs. 99%, p = 0.17), R0 resection rate (92% vs. 96%, p = 0.30), mean dissection speed (16 mm 2 /min vs. 16 mm 2 /min, p = 0.53), and intraoperative perforation rate (5% vs. 6%, p = 0.73). Even when considering cases with poor preoperative scope operability, there were no significant differences between the groups. Comparison of tumors ≥40 mm in diameter between the groups confirmed that the intraoperative perforation rate was significantly lower in the BA‐ESD group than in the C‐ESD group (0% vs. 24%, p = 0.0188). Conclusion SBO is useful for ESD of tumors ≥40 mm in diameter in the proximal colon to prevent intraoperative perforation, which usually has a long procedure time.

Objectives There are some endoscopic resection (ER) methods for neuroendocrine tumors (NETs), however, which method is most useful remains unclear. This study aimed to compare the outcomes of different ER techniques, such as conventional endoscopic mucosal resection (cEMR), endoscopic submucosal dissection (ESD), and endoscopic submucosal resection with a ligation device (ESMR‐L) for rectal NETs. Methods We retrospectively analyzed 96 consecutive patients with 102 rectal NETs of less than 10 mm in diameter who underwent ER between January 2001 and December 2019 at Hiroshima University Hospital. We compared the clinical outcomes of each ER method (cEMR 60 lesions, ESD 21 lesions, and ESMR‐L 21 lesions), divided according to the treatment periods, and evaluated the risk factors for vertical margin (VM) positivity in relation to clinicopathological and endoscopic characteristics. Results As for the mean procedure time, ESD took significantly longer to perform than the other methods. The histological complete resection rate was 80% (48/60) for cEMR, 85.7% (18/21) for ESD, and 100% (21/21) for ESMR‐L, and the VM positive rate was 20% (12/60) for cEMR, 14.3% (3/21) for ESD, and 0% (0/21) for ESMR‐L, with no significant difference. However, the tumor‐front‐to‐VM distance was significantly longer in the ESMR‐L group than in the cEMR and ESD groups. cEMR and ESD were both significant risk factors for VM positivity. No perforation or local recurrence was observed in all methods. Conclusions ESMR‐L is the most useful ER method for small rectal NETs.

Background and Aim The risk of local recurrence might be low in pT1 colorectal carcinoma with a tumor vertical margin (VM) ≥500 μm. We investigated the relationship between endoscopic ultrasonography (EUS) findings and VM in cases with colorectal endoscopic submucosal dissection (ESD) categorized as Type 2B according to the Japan NBI Expert Team (JNET) classification. Methods We analyzed 179 JNET Type 2B colorectal tumors resected by ESD at Hiroshima University Hospital from January 2010 to May 2021. The distance from the tumor invasive front to the muscle layer on EUS was defined as the tumor‐free distance (EUS‐TFD) and classified as Type I (EUS‐TFD ≥1 mm) and II (<1 mm). We investigated the relationship between EUS‐TFD and VM and analyzed the predictive factors for VM ≥500 μm. Results EUS‐TFD Type I was diagnosed in 133 (74.3%) lesions: VM ≥500 μm (114, 85.7%); VM <500 μm (19, 14.3%); and VM positive (VM1) (0, 0%). Type II was diagnosed in 46 (25.7%) lesions: VM ≥500 μm (14, 30.5%); VM <500 μm (22, 47.8%); and VM1 (10, 21.7%). In the EUS‐TFD Type I cases, 84.5% and 87.8% were protruded and superficial types; whereas for Type II cases, these were 38.9% and 25%, respectively. EUS‐TFD classification (Type I), scope operability (good), submucosal invasion depth (<2000 μm), histology at the deepest invasive portion (favorable), and degree of fibrosis (F0/F1) were significant predictors of VM ≥500 μm. Conclusions In JNET Type 2B lesions, EUS‐TFD classification is a novel diagnostic indicator to predict VM ≥500 μm in ESD preoperatively.