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BackgroundDetermining the depth of invasion of early stage colorectal cancer has been emphasized as a means of improving endoscopic diagnostic accuracy. Recent studies have focused on other pathological risk factors for lymph node metastasis (LNM). We investigated the significance of depth of invasion and predictive properties of other endoscopic findings.MethodsWe retrospectively investigated 846 patients with submucosal invasive (T1) colorectal cancer who received an accurate pathological diagnosis and were treated between January 2005 and December 2016. Pathological risk factors associated with LNM were reviewed. We divided patients into groups: low-risk T1 colorectal cancer (LRC; no risk factors) and high-risk T1 colorectal cancer (HRC; exhibiting lymphovascular invasion, tumor budding grade of 2/3, and/or poor differentiation) and studied predictive endoscopic factors for HRC.ResultsSignificant risk factors for LNM in multivariate analysis were lymphovascular invasion [odds ratio (OR) 8.09; 95% confidence interval (CI) 3.84–17.1], tumor budding (OR 1.89; 95% CI 1.09–3.29), and histological differentiation (OR 2.09; 95% CI 1.12–3.89). The LNM-positive rate with only deep submucosal invasion was 1.6%. Significant predictive factors for HRC in multivariate analysis identified rectal tumor location (OR 1.92; 95% CI 1.35 –2.72, depression (OR 2.73; 95% CI 1.96 –3.80), protuberance within the depression (OR 2.58; 95% CI 1.39– 4.78), expansiveness (OR 2.39; 95% CI 1.27– 4.50), and loss of mucosal patterns (OR 1.90; 95% CI 1.20 –3.01) as significant factors.ConclusionsRectal tumor location, depression, protuberance within the depression, expansiveness, and loss of mucosal patterns could be predictive factors for HRC.

BackgroundColorectal endoscopic submucosal dissection (ESD) requires advanced endoscopic skill. For safer and more reliable ESD implementation, various traction devices have been developed in recent years. The purpose of this research was to evaluate whether an ESD training program using a traction device (TD) would contribute to the improvement of trainees’ skill acquisition.MethodsThe differences in treatment outcomes and learning curves by the training program were compared before and after the introduction of TD (control group: January 2014 to March 2016; TD group: April 2016 to June 2018).ResultsA total of 316 patients were included in the analysis (TD group: 202 cases; control group: 114 cases). The number of cases required to achieve proficiency in ESD techniques was 10 in the TD group and 21 in the control group. Compared to the control group, the TD group had a significant advantage in ESD self-completion rate (73.8% vs. 58.8%), dissection speed (19.5 mm2/min vs. 15.9 mm2/min), en bloc resection rate (100% vs. 90%), and R0 resection rate (96% vs. 83%).ConclusionsThe rate of colorectal ESD self-completion by trainees improved immediately after the start of the training program using a traction device compared to the conventional method, and the dissection speed tended to increase linearly with ESD experience. We believe that ESD training using a traction device will help ESD techniques to be performed safely and reliably among trainees.

BackgroundColorectal endoscopic submucosal dissection (ESD) is technically demanding while ensuring safety, especially in cases with fibrosis and/or poor maneuverability. To overcome such difficulties, we developed a novel method called the pocket-creation method with a traction device (PCM with TD). We then evaluated the effectiveness and safety of PCM with TD in colorectal ESD compared to other conventional methods.MethodsIn total, 324 colorectal lesions treated with ESD from July 2018 to June 2019 were included. The following three treatment strategies were used: conventional ESD (CE), CE with TD, and PCM with TD. Patient backgrounds and treatment outcomes were retrospectively compared and analyzed.ResultsAs ESD methods, CE, CE with TD, and PCM with TD account for 58% (187/324), 24% (78/324), and 18% (59/324), respectively. No significant difference was observed among the three groups in en bloc and R0 resection rates or adverse events. The rate of lesions with fibrosis and poor maneuverability was significantly higher in the PCM with TD group (CE group vs CE with TD group vs PCM with TD group: fibrosis, 24% vs 47% vs 64%, p < 0.001; poor maneuverability, 5.3% vs 13% vs 20%, p = 0.002). Dissection speed was significantly higher in the PCM with TD than in the CE with TD group (p = 0.003).ConclusionsPCM with TD can achieve a stable en bloc resection rate and R0 dissection rate without adverse events even in the hands of trainees, irrespective of the size and location of the lesion, presence of fibrosis, and under poor maneuverability conditions.

Objectives This study aimed to extract endoscopic findings for diagnosing colorectal neoplasia associated with sessile serrated lesions (SSLs), which are of significant interest. Methods To compare the magnifying narrow‐band imaging (NBI) findings with microscopic morphology, we classified SSLs into two groups: Group A SSLs included the majority of uniform SSLs and any dysplasia other than that classified as group B SSLs. Group B SSLs included SSLs with intramucosal and invasive carcinoma. We also quantitatively assessed visible vessels using ImageJ software. Results This study included 47 patients with 50 group B SSLs who underwent endoscopic resection between 2012 and 2020. The results were retrospectively compared with those of 237 patients with 311 group A SSLs that underwent endoscopic resection. Using conventional white‐light endoscopy, significantly more group B SSLs had uneven shapes and some reddening compared to group A SSLs. The diagnostic odds ratios for group B SSLs were as follows: lesions with a diameter ≥10 mm, 9.76; uneven shape, 3.79; reddening, 15.46; and visible vessels with NBI, 11.32. Regarding visible vessels with NBI, the specificity and diagnostic accuracy for group B SSLs were 94.9% and 93.1%, respectively. The percentage of the vascular tonal area of NBI images was significantly larger for group B SSLs than for group A SSLs (3.97% vs. 0.29%; p < 0.01). Conclusions SSLs with reddening and/or a diameter ≥10 mm are suspected to contain cancerous components. Moreover, visible vessels observed using magnifying NBI can serve as objective indicators for diagnosing SSLs with cancerous components with a high degree of accuracy.

Background and Aims: We examined the efficacy of the combined use of L-menthol spraying (L-mentholS) as an antispasmodic agent and carbon dioxide insufflation (CO 2 I) on the adenoma detection rate (ADR) in a prospective, single-center trial with a 2 × 2 factorial design. Methods: We randomly assigned 611 patients scheduled to undergo colonoscopy to 4 groups: (1) the L-mentholS + CO 2 I (n = 153), (2) L-mentholS + air insufflation (AI; n = 156), (3) CO 2 I (n = 153), and (4) AI (n = 149) groups. We used 20 mL of 0.8%-L-menthol solution for the L-mentholS. The primary outcome was the difference in the ADR, and the secondary outcomes were the differences in colonic peristalsis and abdominal pain. ­Results: The ADRs were not different among the groups: 1/2/3/4; 39.9%/43.6%/41.2%/51.0%. CO 2 I was associated with a significant decrease in the ADR (OR 0.57; 95% CI 0.35– 0.93) with a multiple logistic regression. The interaction between L-mentholS and CO 2 I was associated with a suppression of the decrease in the ADR. Both L-mentholS and CO 2 I were associated with a significant decrease in abdominal pain, and L-mentholS was associated with a significant improvement of peristalsis. Conclusions: The fact that CO 2 I was associated with significant decreases in the ADR was a problem. The combined use of L-mentholS and CO 2 I could help to suppress the decrease in the ADR.

Purpose The incidence of rectal neuroendocrine tumors (NETs) has been steadily increasing. The risk factors for and prognostic impact of lymph node (LN) metastasis were analyzed in 195 patients with stage I–III rectal NET who underwent radical surgery. Methods This retrospective, single-center study analyzed risk factors for LN metastasis focusing on previously identified factors and a novel risk factor: multiple rectal NETs. The association between LN metastasis and the prognosis was also analyzed. Results Pathologically, the LN metastasis rate (also the rate of stage III disease) was 39%, which was higher than the clinical LN metastasis rate of 14%. Tumor size > 10 mm, presence of central depression, tumor grade G2, depth of invasion, LN swelling on preoperative imaging (cN1), venous invasion and multiple NETs were identified as risk factors for LN metastasis. As the tumor size and risk factors increased, the rate of LN metastasis increased. Among these 7 factors, venous invasion, cN1, and multiple NETs were identified as independent predictors of LN metastasis. LN metastasis of rectal NETs was associated with significantly poor disease-free and disease-specific survival. Conclusions As risk factors increase, the potential for rectal NETs to metastasize to the LNs increases and LN metastasis is associated with a poor prognosis. This is the first study to report multiple NETs as a risk factor for LN metastasis. A future study examining the survival benefit of radical surgery accompanying LN dissection compared with local resection is warranted.

Objectives This ex vivo study evaluated the irrigation efficacy of a new apical negative pressure system (ANP) in canals with simulated immature teeth, by comparing it to EndoVac (EV) system in terms of smear layer (SL) removal and irrigation extrusion. Materials and methods Three millimetres of the root end of 40 single canalled lower incisors were resected and decoronated to standardize root canal length. After instrumentation, the specimens were embedded in warm normal saline agar coloured with 1 % acid red and randomly divided into four groups; one control group and three experimental groups. Except in the control group where distilled water was used as irrigant using positive pressure irrigation needle, the canals were irrigated with 6 % NaOCl and 17 % EDTA using the intracanal negative pressure needle (iNP) system, the EV system or 27G open-ended needle under positive pressure (PP). NaOCl extrusion was determined by observing a discolouration of the agar surrounding the root. The SL was evaluated by observing scanning electron microscope images based on a four-level scoring system. Results Two specimens with irrigant extrusion were observed in the iNP group, which was significantly different (logistic regression, p  < 0.05) to EV and PP. There were no significant differences (Kruskall-Wallis test, p  > 0.05) among the experimental groups in terms of SL removal, but all were significantly different to the control group. Conclusions Irrigation with the iNP could be a viable alternative to EV as an apical negative pressure irrigation technique especially while treating immature teeth. Clinical relevance ANP in canal cleanliness is recommended to be utilized in treating immature teeth where periapical tissues should be saved and stimulated. The iNP system might have the potential to avoid irrigant extrusion while cleaning the canal till the apical end.

Background Recent studies have identified thousands of sense-antisense gene pairs across different genomes by computational mapping of cDNA sequences. These studies have shown that approximately 25% of all transcriptional units in the human and mouse genomes are involved in cis -sense-antisense pairs. However, the number of known sense-antisense pairs remains limited because currently available cDNA sequences represent only a fraction of the total number of transcripts comprising the transcriptome of each cell type. Methods To discover novel antisense transcripts encoded in the antisense strand of important genes, such as cancer-related genes, we conducted expression analyses of antisense transcripts using our custom microarray platform along with 2376 probes designed specifically to detect the potential antisense transcripts of 501 well-known genes suitable for cancer research. Results Using colon cancer tissue and normal tissue surrounding the cancer tissue obtained from 6 patients, we found that antisense transcripts without poly(A) tails are expressed from approximately 80% of these well-known genes. This observation is consistent with our previous finding that many antisense transcripts expressed in a cell are poly(A)-. We also identified 101 and 71 antisense probes displaying a high level of expression specifically in normal and cancer tissues respectively. Conclusion Our microarray analysis identified novel antisense transcripts with expression profiles specific to cancer tissue, some of which might play a role in the regulatory networks underlying oncogenesis and thus are potential targets for further experimental validation. Our microarray data are available at http://www.brc.riken.go.jp/ncrna2007/viewer-Saito-01/index.html .