Underwater vs Conventional Endoscopic Mucosal Resection of Large Sessile or Flat Colorectal Polyps: A Prospective Randomized Controlled Trial

Technical Advances in Endoscopic Resection Techniques for Lower GI Malignancies

Background

The management of bulky neoplastic lesions in the digestive tract has historically been a surgical pursuit. With advancements in endoscopic techniques, particularly endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD), a paradigm shift toward organ preservation has been initiated. These endoscopic methods, developed incrementally since the 1980s, have progressively enabled curative management of lesions with minimal morbidity, challenging the previously unchallenged domain of surgery.

Summary

This review traces the evolution of endoscopic resection from snare polypectomy and EMR to sophisticated ESD, highlighting the technological innovations that have expanded the scope of endoscopic resection. It discusses the intricacies of various EMR techniques like underwater EMR, anchoring EMR, and hybrid EMR, alongside traction-assisted methods and the use of viscous solutions for submucosal injection. Additionally, the manuscript delves into the advancements in ESD, emphasizing traction strategies, knife technology, and the optimization of endoscopes. The benefits of these advancements are weighed against the challenges in anatomopathological interpretation posed by piecemeal resections.

Key Messages

The continuous amelioration of endoscopic resection techniques has significantly improved the outcomes of digestive tract lesion management, particularly in achieving R0 resections and reducing recurrence rates. These advancements represent a monumental step toward minimizing the invasiveness of lesion management. However, despite the progress, the necessity for early follow-up post-EMR remains due to the non-negligible recurrence rates, underscoring the need for a rigorous postoperative surveillance regimen. Furthermore, our review suggests that while ESD has transformed the therapeutic landscape, its widespread adoption hinges on further simplification, safety enhancement, and acceleration of the procedure, possibly through innovations like adaptive traction devices.

Colorectal polypectomy and endoscopic mucosal resection: European Society of Gastrointestinal Endoscopy (ESGE) Guideline - Update 2024

1:  ESGE recommends cold snare polypectomy (CSP), to include a clear margin of normal tissue (1-2 mm) surrounding the polyp, for the removal of diminutive polyps (≤ 5 mm).Strong recommendation, high quality of evidence. 2:  ESGE recommends against the use of cold biopsy forceps excision because of its high rate of incomplete resection.Strong recommendation, moderate quality of evidence. 3:  ESGE recommends CSP, to include a clear margin of normal tissue (1-2 mm) surrounding the polyp, for the removal of small polyps (6-9 mm).Strong recommendation, high quality of evidence. 4:  ESGE recommends hot snare polypectomy for the removal of nonpedunculated adenomatous polyps of 10-19 mm in size.Strong recommendation, high quality of evidence. 5:  ESGE recommends conventional (diathermy-based) endoscopic mucosal resection (EMR) for large (≥ 20 mm) nonpedunculated adenomatous polyps (LNPCPs).Strong recommendation, high quality of evidence. 6:  ESGE suggests that underwater EMR can be considered an alternative to conventional hot EMR for the treatment of adenomatous LNPCPs.Weak recommendation, moderate quality of evidence. 7:  Endoscopic submucosal dissection (ESD) may also be suggested as an alternative for removal of LNPCPs of ≥ 20 mm in selected cases and in high-volume centers.Weak recommendation, low quality evidence. 8:  ESGE recommends that, after piecemeal EMR of LNPCPs by hot snare, the resection margins should be treated by thermal ablation using snare-tip soft coagulation to prevent adenoma recurrence.Strong recommendation, high quality of evidence. 9:  ESGE recommends (piecemeal) cold snare polypectomy or cold EMR for SSLs of all sizes without suspected dysplasia.Strong recommendation, moderate quality of evidence. 10:  ESGE recommends prophylactic endoscopic clip closure of the mucosal defect after EMR of LNPCPs in the right colon to reduce to reduce the risk of delayed bleeding.Strong recommendation, high quality of evidence. 11:  ESGE recommends that en bloc resection techniques, such as en bloc EMR, ESD, endoscopic intermuscular dissection, endoscopic full-thickness resection, or surgery should be the techniques of choice in cases with suspected superficial invasive carcinoma, which otherwise cannot be removed en bloc by standard polypectomy or EMR.Strong recommendation, moderate quality of evidence.

Standardised training for endoscopic mucosal resection of large non-pedunculated colorectal polyps to reduce recurrence (*STAR-LNPCP study): a multicentre cluster randomised trial

OBJECTIVE

Endoscopic mucosal resection (EMR) is the preferred treatment for non-invasive large (≥20 mm) non-pedunculated colorectal polyps (LNPCPs) but is associated with an early recurrence rate of up to 30%. We evaluated whether standardised EMR training could reduce recurrence rates in Dutch community hospitals.

DESIGN

In this multicentre cluster randomised trial, 59 endoscopists from 30 hospitals were randomly assigned to the intervention group (e-learning and 2-day training including hands-on session) or control group. From April 2019 to August 2021, all consecutive EMR-treated LNPCPs were included. Primary endpoint was recurrence rate after 6 months.

RESULTS

A total of 1412 LNPCPs were included; 699 in the intervention group and 713 in the control group (median size 30 mm vs 30 mm, 45% vs 52% size, morphology, site and access (SMSA) score IV, 64% vs 64% proximal location). Recurrence rates were lower in the intervention group compared with controls (13% vs 25%, OR 0.43; 95% CI 0.23 to 0.78; p=0.005) with similar complication rates (8% vs 9%, OR 0.93; 95% CI 0.64 to 1.36; p=0.720). Recurrences were more often unifocal in the intervention group (92% vs 76%; p=0.006). In sensitivity analysis, the benefit of the intervention on recurrence rate was only observed in the 20-40 mm LNPCPs (5% vs 20% in 20-29 mm, p=0.001; 10% vs 21% in 30-39 mm, p=0.013) but less evident in ≥40 mm LNPCPs (24% vs 31%; p=0.151). In a post hoc analysis, the training effect was maintained in the study group, while in the control group the recurrence rate remained high.

CONCLUSION

A compact standardised EMR training for LNPCPs significantly reduced recurrences in community hospitals. This strongly argues for a national dedicated training programme for endoscopists performing EMR of ≥20 mm LNPCPs. Interestingly, in sensitivity analysis, this benefit was limited for LNPCPs ≥40 mm.

TRIAL REGISTRATION NUMBER

NTR7477.

Underwater versus conventional endoscopic mucosal resection for ≥10 mm sessile or flat colorectal polyps: A systematic review and meta-analysis

BACKGROUND AND AIM

Underwater endoscopic mucosal resection (UEMR) has been an emerging substitute for conventional EMR (CEMR). This systematic review and meta-analysis aimed at comparing the efficiency and safety of the two techniques for removing ≥10 mm sessile or flat colorectal polyps.

METHODS

PubMed, Cochrane Library and Embase databases were searched up to February 2023 to identify eligible studies that compared the outcomes of UEMR and CEMR. This meta-analysis was conducted on the en bloc resection rate, R0 resection rate, complete resection rate, procedure time, adverse events rate and recurrence rate.

RESULTS

Nine studies involving 1,727 colorectal polyps were included: 881 were removed by UEMR, and 846 were removed by CEMR. UEMR was associated with a significant increase in en bloc resection rate [Odds ratio(OR) 1.69, 95% confidence interval(CI) 1.36-2.10, p<0.00001, I2 = 33%], R0 resection rate(OR 1.52, 95%CI 1.14-2.03, p = 0.004, I2 = 31%) and complete resection rate(OR 1.67, 95%CI 1.06-2.62, p = 0.03, I2 = 0%) as well as a significant reduction in procedure time(MD ‒4.27, 95%CI ‒7.41 to ‒1.13, p = 0.008, I2 = 90%) and recurrence rate(OR 0.52, 95%CI 0.33-0.83, p = 0.006, I2 = 6%). Both techniques were comparable in adverse events rate.

CONCLUSION

UEMR can be a safe and efficient substitute for CEMR in removing ≥10 mm sessile or flat colorectal polyps. More studies verifying the advantages of UEMR over CEMR are needed to promote its application.

Feasibility and Efficacy of Gastric Underwater Endoscopic Mucosal Resection

Gastric cancer, a leading cause of cancer-related deaths globally, necessitates effective and early detection and treatment strategies. Endoscopic resection techniques, particularly endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD), have evolved significantly, enhancing the treatment of gastric neoplasms. Underwater endoscopic mucosal resection (UEMR) is a widely used technique for the resection of duodenal and colorectal neoplasms. However, the feasibility and efficacy of UEMR in the stomach are not well established. This retrospective observational study, conducted at a tertiary medical center, evaluated the efficacy and safety of UEMR in 81 patients with gastric neoplasms. Thus, it indicates that UEMR is a highly effective and safe technique for managing small to medium-sized gastric neoplasms, achieving 100% en bloc and 93.8% R0 resection rates with a low incidence of complications. Moreover, the procedure time was found to be significantly shorter for UEMR compared to ESD, thus highlighting its efficiency. While UEMR demonstrates high safety and efficacy, it is not suitable for all patients, with some requiring conversion to ESD as a treatment option. Despite the promising results, broader validation through extensive and randomized trials is recommended to establish UEMR as a standard approach in gastric cancer management.

Treatment for T1 colorectal cancers substratified by site and size: "horses for courses"

Background

Owing to advances in diagnostic technology, the diagnosis of T1 colorectal cancers (CRCs) continues to increase. However, the optimal management of T1 CRCs in the Western Hemisphere remains unclear due to limited population-based data directly comparing the efficacy of endoscopic therapy (ET) and surgical resection (SR). The purpose of this study was to report outcome data from a large Western cohort of patients who underwent ET or SR for early CRCs.

Methods

The SEER-18 database was used to identify patients with T1 CRCs diagnosed from 2004 to 2018 treated with ET or SR. Multivariable logistic regression models were employed to identify variables related to lymph node metastasis (LNM). Rates of ET and 1-year relative survival were calculated for each year. Effect of ET or SR on overall survival and cancer-specific survival was compared using Kaplan-Meier method stratified by tumor size and site.

Results

A total of 28,430 T1 CRCs patients were identified from 2004 to 2018 in US, with 22.7% undergoing ET and 77.3% undergoing SR. The incidence of T1 CRCs was 6.15 per 100,000 person-years, with male patients having a higher incidence. Left-sided colon was the most frequent location of tumors. The utilization of ET increased significantly from 2004 to 2018, with no significant change in 1-year relative survival rate. Predictors of LNM were age at diagnosis, sex, race, tumor size, histology, grade, and location. The 5-year relative survival rates were 91.4 and 95.4% for ET and SR, respectively. Subgroup analysis showed that OS and CSS were similar between ET and SR in T1N0M0 left-sided colon cancers with tumors 2 cm or less and in rectal cancers with tumors 1 cm or less.

Conclusion

Our study showed that ET was feasible and safe for patients with left-sided T1N0M0 colon cancers and tumors of 2 cm or less, as well as T1N0M0 rectal cancers and tumors of 1 cm or less. Therefore, the over- and under-use of ET should be avoided by carefully selecting patients based on tumor size and site.

Outcomes for Underwater Endoscopic Mucosal Resection and Endoscopic Submucosal Dissection of 21-30-mm Colorectal Polyps: A Feasible Study

BACKGROUND AND AIMS

This randomized controlled trial (RCT) was designed to evaluate the short-term outcomes of underwater endoscopic mucosal resection (UEMR) and endoscopic submucosal dissection (ESD) of 21-30 mm colonic polyps.

METHOD

We conducted a single-center RCT. Patients diagnosed with suspected colorectal intramucosal carcinoma (21-30 mm and adaptable for both UEMR and ESD) were randomly assigned to the UEMR and ESD groups at a 1:1 ratio. The primary endpoint was the R0 resection rate. We independently performed one-sample tests against the set threshold for each treatment. The significance level was set at p = 0.224.

RESULT

Eleven polyps each in the UEMR and ESD groups, respectively, were analyzed. The R0 resection rate (%) was 36 (95% confidence interval 11-69) and 100 (72-100) for UEMR and ESD, respectively, with a significant difference between the two groups (p = 0.002). The p-value against the set threshold for UEMR was 0.743, whereas that for ESD was < 0.001 (one-sample binomial test). The en bloc resection rates (%) were 82 (48-97) and 100 (72-100) for UEMR and ESD, respectively; however, no significant difference was observed (p = 0.167). The mean treatment time (min) was significantly shorter in the UEMR group (8 ± 6) than in the ESD group (48 ± 29) (p = 0.001).

CONCLUSION

ESD could achieve a high R0 resection rate, while the en bloc resection rate was comparable between the two treatment techniques with less burden on patients undergoing UEMR for 21-30-mm colorectal polyps.

CLINICAL TRIAL REGISTRATION

The study was registered at the Japan Registry of Clinical Trial as jRCT1030210015 and jRCT1030210177.

Cap-assisted endoscopic mucosal resection as a salvage technique for challenging colorectal laterally spreading tumors

BACKGROUND

Cap-assisted endoscopic mucosal resection (EMR-c) has emerged as a potential alternative to standard piecemeal wide-field EMR (WF-EMR) for the resection of laterally spreading tumors (LSTs). However, clear indications for this technique are still lacking. Our objective was to investigate the performance of salvage EMR-c after WF-EMR failure in the resection of large colorectal LSTs.

METHODS

The data of consecutive patients undergoing WF-EMR for large colorectal LSTs (2015-2021) were analyzed in this single-center, retrospective, observational study. In the event of a WF-EMR failure, the procedure was switched to EMR-c in the same session. The efficacy of the two techniques was evaluated in terms of complete endoscopic resection, R0 resection, and recurrence rate. Safety was also assessed.

RESULTS

Overall, the data from 81 WF-EMRs were collected. Eighteen cases of WF-EMR failure were switched to EMR-c in the same session and complete endoscopic resection was achieved in 17/18 patients (94.4%). No statistically significant difference was observed between WF-EMR and salvage EMR-c in terms of macroscopic radicality (P = 0.40) and R0 resection (P = 0.12). However, recurrence was more common with EMR-c (44.4% vs. 23.5%; P = 0.05), as were adverse events, particularly intraprocedural bleeding (27.8% vs. 7.9%; P = 0.04).

CONCLUSION

EMR-c is an effective salvage technique for challenging colorectal LSTs following WF-EMR failure. Due to the elevated risk of adverse events associated with this procedure, careful patient selection, endoscopic expertise, and close follow-up are strongly recommended.

Underwater versus conventional endoscopic mucosal resection for colorectal lesions: An updated meta-analysis of randomized controlled trials

Background and study aims Colorectal malignancy is a leading cause of death. Conventional endoscopic mucosal resection (CEMR) is a strategy used to resect precancerous lesions that involves injecting fluid beneath a polyp to create a gap for resection. Underwater endoscopic mucosal resection (UEMR) is a newer method that forgoes injection, instead filling the intestinal cavity with water to facilitate polyp resection. Our aim was to compare the safety and efficacy of these approaches by synthesizing the most contemporary evidence. Methods PubMed, Embase, and Cochrane libraries were searched from inception through November 11, 2022 for randomized controlled trials (RCTs) comparing UEMR and CEMR for resection of colorectal lesions. The primary outcome was the rate of en bloc resection and secondary outcomes included recurrence, procedure time, and adverse events (AEs). Results A total of 2539 studies were identified through our systematic literature search. After screening, seven RCTs with a total of 1581 polyps were included. UEMR was associated with significantly increased rates of en bloc resection (RR 1.18 [1.03, 1.35]; I 2 = 76.6%) versus conventional approaches. No significant differences were found in procedure time, recurrence, or AEs. Conclusions UEMR is a promising effective technique for removal of colorectal lesions. The most contemporary literature indicates that it improves en bloc resection rate without increasing procedure time, recurrence, or AEs (PROSPERO ID CRD42022374935).

Comparing endoscopic mucosal resection with endoscopic submucosal dissection in colorectal adenoma and tumors: Meta-analysis and system review

AIMS

This study aimed to evaluate the safety, efficacy, and long-term outcomes of endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) for treating colorectal adenomas and tumors.

METHODS

A systematic literature review was conducted using databases including PubMed, Web of Science, and Embase. Parameters such as number of patients or lesions, histological diagnosis, lesion size, surgery time, en-bloc resection, R0 resection, severe postoperative complications, and local recurrence were extracted and pooled for analysis.

RESULTS

A total of 12 retrospective studies involving 1289 patients and 1850 lesions were included in the analysis. EMR was found to have a shorter operation time by 53.6 minutes (95% CI: 51.3, 55.9, P<0.001) and fewer incidences of severe postoperative complications such as perforation and delayed bleeding (OR = 0.40, 95%CI: 0.23, 0.71, P<0.001). On the other hand, ESD had higher rates of en-bloc resection (OR = 0.15, 95%CI: 0.07, 0.30, P<0.001) and R0 resection (OR = 0.32, 95%CI: 0.16, 0.65, P<0.001). Recurrence after EMR was found to be significantly higher than that after ESD surgery (OR = 5.88, 95%CI: 2.15, 16.07, P = 0.037).

CONCLUSIONS

The study suggests that the choice of surgical method may have a greater impact on recurrence compared to the pathological type, and that ESD may be more suitable for the treatment of malignant lesions despite its higher rates of severe postoperative complications and longer operation time.

Safety and efficacy of underwater versus conventional endoscopic mucosal resection for colorectal polyps: Systematic review and meta-analysis of RCTs

Background and study aims Conventional endoscopic mucosal resection (C-EMR) is limited by low en-bloc resection rates, especially for large (> 20 mm) lesions. Underwater EMR (U-EMR) has emerged as an alternative for colorectal polyps and is being shown to improve en-bloc resection rates. We conducted a systematic review and meta-analysis comparing the two techniques. Methods Multiple databases were searched through November 2022 for randomized controlled trials (RCTs) comparing outcomes of U-EMR and C-EMR for colorectal polyps. Meta-analysis was performed to determine pooled proportions and relative risks (RRs) of R0 and en-bloc resection, polyp recurrence, resection time, and adverse events. Results Seven RCTs with 1458 patients (U-EMR: 739, C-EMR: 719) were included. The pooled rate of en-bloc resection was significantly higher with U-EMR vs C-EMR, 70.17% (confidence interval [CI] 46.68-86.34) vs 58.14% (CI 31.59-80.68), respectively, RR 1.21 (CI 1.01-1.44). R0 resection rates were higher with U-EMR vs C-EMR, 58.1% (CI 29.75-81.9) vs 44.6% (CI 17.4-75.4), RR 1.25 (CI 0.99-1.6). For large polyps (> 20 mm), en-bloc resection rates were comparable between the two techniques, RR 1.24 (CI 0.83-1.84). Resection times were comparable between U-EMR and C-EMR, standardized mean difference -1.21 min (CI -2.57 to -0.16). Overall pooled rates of perforation, and immediate and delayed bleeding were comparable between U-EMR and C-EMR. Pooled rate of polyp recurrence at surveillance colonoscopy was significantly lower with U-EMR than with C-EMR, RR 0.62 (CI 0.41-0.94). Conclusions Colorectal U-EMR results in higher en-bloc resection and lower recurrence rates when compared to C-EMR. Both techniques have comparable resection times and safety profiles.

[Interventional endoscopy in gastroenterology]

Essential innovations in interventional endoscopy have significantly broadened the treatment armamentarium in gastroenterology. The treatment and complication management of intraepithelial neoplasms and early forms of cancer are increasingly being primarily addressed endoscopically. In cases of endoluminal lesions with no risk of lymph node or distant metastases, endoscopic mucosal resection and endoscopic submucosal dissection have become established as standards. For broad-based adenomas, coagulation of the resection margins should be performed in the case of a piecemeal resection. Submucosal lesions can be reached and resected by tunneling techniques. Peroral endoscopic myotomy in cases of achalasia is a new treatment option for hypertensive and hypercontractile motility disorders. In addition, endoscopic myotomy for gastroparesis has shown very promising results. In this article, new resection techniques and so-called third space endoscopy are presented and critically discussed.

Cold resection for colorectal polyps: where we are and where we are going?

INTRODUCTION

Endoscopic resection of colonic precancerous lesions has been demonstrated to significantly decrease colorectal cancer (CRC) incidence and mortality. Among resection techniques, cold snare polypectomy (CSP) has been shown as a highly feasible, effective and safe option and is widely used in clinical practice, being regarded as the first-line technique for removal of small and diminutive colorectal polyps. On the other hand, conventional hot snare polypectomy (HSP) and endoscopic mucosal resection (EMR), namely the gold standard treatments for larger polyps, may be occasionally associated to complications due to electrocautery injury.

AREAS COVERED

To overcome these shortcomings of electrocautery-based resection techniques, in the last few years CSP has been increasingly assessed as a treatment option for additional indications, with a focus on nonpedunculated colorectal polyps ≥10 mm.

EXPERT OPINION

This review aims to present current and widened indications of CSP discussing the latest findings from the most remarkable studies, with an insight into technical issues, novelties and potential advances in the near future.

Underwater versus conventional EMR of large nonpedunculated colorectal lesions: a multicenter randomized controlled trial

BACKGROUND AND AIMS

Underwater EMR (UEMR) is an alternative procedure to conventional EMR (CEMR) to treat large, nonpedunculated colorectal lesions (LNPCLs). In this multicenter, randomized controlled clinical trial, we aimed to compare the efficacy and safety of UEMR versus CEMR on LNPCLs.

METHODS

We conducted a multicenter, randomized controlled clinical trial from February 2018 to February 2020 in 11 hospitals in Spain. A total of 298 patients (311 lesions) were randomized to the UEMR (n = 149) and CEMR (n = 162) groups. The main outcome was the lesion recurrence rate in at least 1 follow-up colonoscopy. Secondary outcomes included technical aspects, en bloc resection rate, R0 resection rates, and adverse events, among others.

RESULTS

There were no differences in the overall recurrence rate (9.5% UEMR vs 11.7% CEMR; absolute risk difference, -2.2%; 95% CI, -9.4 to 4.9). However, considering polyp sizes between 20 and 30 mm, the recurrence rate was lower for UEMR (3.4% UEMR vs 13.1% CEMR; absolute risk difference, -9.7%; 95% CI, -19.4 to 0). The R0 resection showed the same tendency, with significant differences favoring UEMR only for polyps between 20 and 30 mm. Overall, UEMR was faster and easier to perform than CEMR. Importantly, the techniques were equally safe.

CONCLUSIONS

UEMR is a valid alternative to CEMR for treating LNPCLs and could be considered the first option of treatment for lesions between 20 and 30 mm due to its higher en bloc and R0 resection rates. (Clinical trial registration number: NCT03567746.).

Underwater versus conventional endoscopic mucosal resection for sessile colorectal polyps: an updated systematic review and meta-analysis

BACKGROUND

underwater endoscopic mucosal resection (uEMR) without submucosal injection for sessile colorectal polyps was introduced as a new replacement for conventional EMR (cEMR). However, the optimal resection strategy remains a topic of debate. Hence, this meta-analysis was performed to compare the efficacy and safety of uEMR and cEMR in patients with sessile colorectal polyps.

METHODS

a comprehensive search of the literature from 2000 till January 2022 was performed from Medline, CENTRAL and Embase for randomized controlled trials (RCTs) comparing cEMR vs uEMR for colorectal polyps. The evaluated outcomes included en bloc resection, R0 resection, procedure time, overall bleeding and recurrence. Pooled risk ratios (RR) with 95 % confidence interval were calculated using a random effect model.

RESULTS

six studies were included, out of which four were full-text articles and two were conference abstracts. En bloc resection (RR 1.26, 95 % CI: 1.00-1.60), R0 resection (RR 1.10, 95 % CI: 0.96-1.26), overall bleeding (RR 0.85, 95 % CI: 0.54-1.34) and recurrence rate (RR 0.75, 95 % CI: 0.45-1.27) were comparable between uEMR and cEMR. However, uEMR was associated with a shorter procedure time (mean difference [MD] -1.55 minutes, 95 % CI: -2.71 to -0.39). According to the subgroup analysis, uEMR led to a higher rate of en bloc resection (RR 1.41, 95 % CI: 1.07-1.86) and R0 resection (RR 1.19, 95 % CI: 1.01-1.41) for polyps ≥ 10 mm in size.

CONCLUSION

both uEMR and cEMR have a comparable safety and efficacy. For polyps larger than 10 mm, uEMR may have an advantage over cEMR and should be the topic for future studies.

Underwater versus conventional EMR for nonpedunculated colorectal lesions: a randomized clinical trial

BACKGROUND AND AIMS

Conventional endoscopic mucosal resection (CEMR) is the standard modality for removing nonpedunculated colorectal lesions. Underwater endoscopic mucosal resection (UEMR) has emerged as an alternative method. There are few comparative studies between these techniques, especially evaluating recurrence. Therefore, the purpose of this trial was to compare CEMR and UEMR for the resection of colorectal lesions with respect to efficacy, safety, and recurrence rate.

METHODS

This was a randomized controlled trial of UEMR versus CEMR for naïve and nonpedunculated lesions measuring between 10 and 40 mm. The primary outcome was adenoma recurrence at 6 months after the resection. Secondary outcomes were rates of technical success, en bloc resection, and adverse events. Block randomization was used to assign patients. Tattooing was performed to facilitate localization of the scars and eventual recurrences. Endoscopic follow-up was scheduled at 6 months after the procedure. The sites of resections were examined with white-light imaging, narrow-band imaging (NBI), and conventional chromoscopy with indigo carmine followed by biopsies.

RESULTS

One hundred five patients with 120 lesions were included, with a mean size of 17.5 ± 7.1 (SD) mm. Sixty-one lesions were resected by UEMR and 59 by CEMR. The groups were similar at baseline regarding age, sex, average size, and histologic type. Lesions in the proximal colon in the CEMR group corresponded to 83% and in the UEMR group to 67.8% (P = .073). There was no difference between groups regarding success rate (1 failure in each group) and en bloc resection rate (60.6% UEMR vs 54.2% CEMR, P = .48). Intraprocedural bleeding was observed in 5 CEMRs (8.5%) and 2 UEMRs (3.3%) (P = .27). There was no perforation or delayed hemorrhage in either groups. Recurrence rate was higher in the CEMR arm (15%) than in the UEMR arm (2%) (P = .031). Therefore, the relative risk of 6-month recurrence rate in the CEMR group was 7.5-fold higher (95% CI, 0.98-58.20), with a number needed to treat of 7.7 (95% CI, 40.33-4.22). The higher recurrence rate in the CEMR group persisted only for lesions measuring 21 to 40 mm (35.7% vs 0%; P = .04).

CONCLUSION

This study demonstrated that UEMR was associated with a lower adenoma recurrence rate than was CEMR. Both endoscopic techniques were effective and had similar rates of adverse events for the treatment of nonpedunculated colorectal lesions.

[Current endoscopic resection techniques in the colorectum: possibilities, perspectives, limitations]

Since the first endoscopic polypectomies have been performed, the resection of premalignant lesions during colonoscopy has become a success story in the field of gastroenterology: Incidence and mortality of colorectal cancer have been significantly reduced with the implementation of screening programs. Most polyps in the lower gastrointestinal tract are small and easy to remove. However, larger polyps, early carcinomas and subepithelial lesions can be removed with modern endoscopic resection techniques as well. Minimally invasive endoscopic resections offer an organ-preserving alternative to surgery in a growing number of patients. In this review, we discuss the advantages and limitations of traditional and novel endoscopic resection techniques, including endoscopic mucosal resection, endoscopic submucosal dissection and endoscopic full thickness resection.

Feasibility of progressive polyp contraction with underwater endoscopic mucosal resection in ≥ 20 mm superficial colorectal lesions

Background and study aims  Underwater endoscopic mucosal resection (UEMR) does not always result in en bloc resection of large colorectal lesions. The aim of this study was to demonstrate the feasibility of en bloc resection with progressive polyp contraction with underwater endoscopic mucosal resection (PP-CUE) of large, superficial colorectal lesions. The advantage of PP-CUE is to enable resection of a superficial non-polypoid lesion that is larger than the snare diameter. Patients and methods  Eleven consecutive lesions in ten patients who underwent UEMR with PP-CUE of large superficial colorectal lesions (20 mm or greater) were included. Results  The median lesion diameter was 24 mm (interquartile range [IQR], 20-24 mm). All lesions were larger than the 15-mm rotatable snare that was used. Median procedure time and PP-CUE time were 11 minutes (IQR, 8.5-12.3) and 2.3 minutes (IQR, 1.9-3.4), respectively. Pathological diagnoses of resected specimens included six adenomas, three sessile serrated lesions, and two slightly invasive submucosal carcinomas. En bloc and R0 resection rates were both 91 % (10/11). No adverse events occurred. Conclusions  PP-CUE is useful to resect superficial non-polypoid colorectal lesions 20 to 25 mm in diameter in an en bloc fashion.

Endoscopic mucosal resection-precutting vs conventional endoscopic mucosal resection for sessile colorectal polyps sized 10-20 mm

BACKGROUND

The optimal method to remove sessile colorectal lesions sized 10-20 mm remains uncertain. Piecemeal and incomplete resection are major limitations in current practice, such as endoscopic mucosal resection (EMR) and cold or hot snare polypectomy. Recently, EMR with circumferential precutting (EMR-P) has emerged as an effective technique, but the quality of current evidence in comparative studies of conventional EMR (CEMR) and EMR-P is limited.

AIM

To investigate whether EMR-P is superior to CEMR in removing sessile colorectal polyps.

METHODS

This multicenter randomized controlled trial involved seven medical institutions in China. Patients with colorectal polyps sized 10-20 mm were enrolled and randomly assigned to undergo EMR-P or CEMR. EMR-P was performed following submucosal injection, and a circumferential mucosa incision (precutting) was conducted using a snare tip. Primary outcomes included a comparison of the rates of en bloc and R0 resection, defined as one-piece resection and one-piece resection with histologically assessed clear margins, respectively.

RESULTS

A total of 110 patients in the EMR-P group and 110 patients in the CEMR group were finally evaluated. In the per-protocol analysis, the proportion of en bloc resections was 94.3% [95% confidence interval (CI): 88.2%-97.4%] in the EMR-P group and 86% (95%CI: 78.2%-91.3%) in the CEMR group (P = 0.041), while subgroup analysis showed that for lesions > 15 mm, EMR-P also resulted in a higher en bloc resection rate (92.0% vs 58.8% P = 0.029). The proportion of R0 resections was 81.1% (95%CI: 72.6%-87.4%) in the EMR-P group and 76.6% (95%CI: 68.8%-84.4%) in the CEMR group (P = 0.521). The EMR-P group showed a longer median procedure time (6.4 vs 3.0 min; P < 0.001). No significant difference was found in the proportion of patients with adverse events (EMR-P: 9.1%; CEMR: 6.4%; P = 0.449).

CONCLUSION

In this study, EMR-P served as an alternative to CEMR for removing nonpedunculated colorectal polyps sized 10-20 mm, particularly polyps > 15 mm in diameter, with higher R0 and en bloc resection rates and without increasing adverse events. However, EMR-P required a relatively longer procedure time than CEMR. Considering its potential benefits for en bloc and R0 resection, EMR-P may be a promising technique in colorectal polyp resection.

Research trends on endoscopic mucosal resection: A bibliometric analysis from 1991 to 2021

Background

In recent years, the rapid development of digestive endoscopy technology has brought revolutionary changes to endoscopic therapy. A growing number of articles have been published annually. We aimed to explore global scientific outputs and hotspots of endoscopic mucosal resection (EMR) published by different countries, organizations, and authors.

Methods

We extracted relevant publications from the Web of Science Core Collection (WOSCC) on June 23, 2022. We examined the retrieved data by bibliometric analysis (e.g., cocited and cluster analysis, keyword co-occurrence) using the software CiteSpace and VOSviewer to analyze and predict the trends and hot spots in this field.

Results

A total of 2,695 papers were finally identified. The results showed that the number of articles fluctuated with the year and reached its peak in 2021. NATIONAL CANCER CENTER JAPAN was the most influential institution. MICHAEL J BOURKE and YUTAKA SAITO are two of the most prolific scholars. ENDOSCOPY and GASTROINTESTINAL ENDOSCOPY were the most productive journals. “Early gastric cancer” and “Barrett's esophagus” were the focus of EMR research. “Adverse events”, “cold snare polypectomy” and “outcomes” have become increasingly popular in recent years and could become hot spots in the future.

Conclusion

In this study, we summarized the characteristics of the publications; identified the most influential countries, institutions, and journals; and identified the leading topics in the EMR field.

Underwater versus conventional endoscopic mucosal resection for superficial non-ampullary duodenal epithelial tumors ≤20mm: A systematic review and meta-analysis

BACKGROUND AND AIMS

Underwater endoscopic mucosal resection (UEMR) is an emerging technique for endoscopic resection of superficial non-ampullary duodenal epithelial tumors (SNADETs). However, compared to conventional EMR, its efficacy and safety has not been widely explored.

METHODS

We conducted a comprehensive search using the Pubmed, Embase, and Cochrane Library databases to identify studies comparing the efficacy and safety of UEMR versus EMR for SNADETs. The main outcomes examined included en bloc resection rate, R0 resection rate, recurrence rate, procedure time, and adverse events.

RESULTS

A total of 5 studies comprising 635 patients were included. All the literature included duodenal lesions smaller than 20 mm. The pooled analysis showed that UEMR could achieve a higher en bloc resection rate (OR 1.78, 95%CI: 1.17 to 2.71, P = 0.007) and shorter procedure time (MD -4.08, 95%CI: -6.44 to -1.73, P = 0.0007) than EMR. However, the pooled results did not support a superiority of UEMR over EMR for R0 resection rate (OR 1.27; 95% CI: 0.90 to 1.81, P = 0.18) or recurrence rate (OR 0.49; 95% CI: 0.15 to 1.67, P = 0.26). The occurrence of adverse events, including postoperative bleeding, intraoperative perforation, and delayed perforation, was very low in included studies.

CONCLUSION

Compared to EMR, UEMR is an effective and safe technique for SNADETs ≤20 mm.

Underwater endoscopic mucosal resection for rectal neuroendocrine tumors (with videos): a single center retrospective study

BACKGROUND

Underwater endoscopic mucosal resection (UMER) is a new method of endoscopic resection to completely remove the lesion without submucosal injection. But few attempts have been carried out for rectal neuroendocrine tumors (rectal NETs).

METHODS

We retrospectively investigated data on the tumor characteristics and outcomes of patients with ≤ 10 mm rectal NETs who underwent UEMR or endoscopic submucosal dissection (ESD) from January 2019 to June 2021 in our institute.

RESULTS

The endoscopic resection rate was 100% in both UEMR and ESD groups. The histological complete resection rate of the UEMR group (95.5%) was lower than that of the ESD group (96.4%) with no significant difference. The average operation time, hospitalization time and operation cost of UEMR group were less than those of ESD group (P < 0.05). The incidence of postoperative abdominal pain and abdominal distention in the UEMR group was lower than that in the ESD group (P < 0.05). There was no significant difference in the incidence of delayed bleeding and perforation between the two groups. There was no local recurrence or distant metastasis in the two groups during the follow-up period.

CONCLUSIONS

Both the UEMR and ESD can effectively treat ≤ 10 mm rectal NETs with invasion depth confined to the mucosa and submucosa. UEMR is superior to ESD in operation time, hospitalization time, operation cost, postoperative abdominal pain and abdominal distention.

Underwater endoscopic mucosal resection for colorectal lesions: Can it be an “Underwater” revolution?

Underwater endoscopic mucosal resection (UEMR) is a newly developed technique for the removal of colorectal, duodenal, esophageal, gastric, ampullary, and small intestinal lesions. We performed a PubMed literature search for articles reporting UEMR outcomes for colorectal polyps. Four randomized controlled trials, nine non‐randomized prospective trials, 16 retrospective studies, and 27 case reports were selected for assessment of the efficacy and safety of UEMR. We summarized the therapeutic outcomes of UEMR in each category according to the lesion characteristics [small size (<10 mm), intermediate size (10–19 mm), large size (≥20 mm), recurrent lesion, and rectal neuroendocrine tumor], and calculated the incidence of adverse events among the included articles. As the treatment outcomes for small polyps appeared similar between UEMR and conventional endoscopic mucosal resection (CEMR), UEMR can be a standard procedure for small colorectal polyps suspicious for high‐grade dysplasia to avoid incomplete removal of occult invasive cancer by cold snare polypectomy. As UEMR showed satisfactory outcomes for intermediate‐size lesions and recurrent lesions after endoscopic resection, UEMR can be a standard procedure for these lesions. Regarding large lesions and rectal neuroendocrine tumors, comparisons of UEMR with current standard methods for them were lacking, and further investigations are warranted. Adverse events appeared comparable or less frequent for UEMR compared with CEMR but still existed. Therefore, careful implementation of this new technique in clinical practice is important for its widespread use.

Comparison of precutting endoscopic mucosal resection and endoscopic submucosal dissection for large (20-30 mm) flat colorectal lesions

BACKGROUND AND AIM

The complete and safe removal of large (≥ 20 mm) colorectal lesions is an area of concern. Endoscopic submucosal dissection (ESD) effectively removes these lesions compared with endoscopic mucosal resection (EMR). However, ESD requires advanced techniques, longer procedure time, and high cost. Precutting EMR (EMR-P) is a modified EMR method that overcomes the limitations of EMR. This study aimed to compare the efficacy and safety of EMR-P and ESD in large (20-30 mm) flat colorectal lesions.

METHODS

This was a retrospective analysis of cases in which 20- to 30-mm flat colorectal lesions were resected at Seoul St. Mary's Hospital from January 2014 to December 2019. Propensity score matching was performed to control for possible confounders.

RESULTS

Two hundred and ninety-nine patients were included in this study. After matching, 90 patients were assigned to each group. There were no significant difference in complete resection rates (92.2% vs 92.2%, P = 1.000), en bloc resection rates (95.6% vs 97.8%, P = 0.682), and mean size of lesions (22.9 ± 3.1 mm vs 23.0 ± 3.1 mm, P = 0.867) between EMR-P and ESD. Procedure time was significantly shorter with EMR-P (11.0 ± 6.5 min vs 37.0 ± 19.3 min, P < 0.001). The adverse events rate was not significantly different between both groups. No local recurrence occurred in both groups.

CONCLUSIONS

Precutting EMR was not significantly different to ESD in terms of complete resection rate and en bloc resection rate for 20- to 30-mm flat colorectal lesions without fibrosis. Furthermore, EMR-P has shorter procedure time than ESD. EMR-P could be considered one of standard treatments for large flat colorectal lesions.

Delayed Bleeding After Endoscopic Resection of Colorectal Polyps: Identifying High-Risk Patients

Delayed post-polypectomy bleeding (DPPB) is a potentially severe complication of therapeutic colonoscopy which can result in hospital readmission and re-intervention. Over the last decade, rates of DPPB reported in the literature have fallen from over 2% to 0.3–1.2%, largely due to improvements in resection technique, a shift towards cold snare polypectomy, better training, adherence to guidelines on periprocedural antithrombotic management, and the use of antithrombotics with more favourable bleeding profiles. However, as the complexity of polypectomy undertaken worldwide increases, so does the importance of identifying patients at increased risk of DPPB. Risk factors can be categorised according to patient, polyp and personnel related factors, and their integration together to provide an individualised risk score is an evolving field. Strategies to reduce DPPB include safe practices relevant to all patients undergoing colonoscopy, as well as specific considerations for patients identified to be high risk. This narrative review sets out an evidence-based summary of factors that contribute to the risk of DPPB before discussing pragmatic interventions to mitigate their risk and improve patient safety.