Current status and future perspectives of endoscopic diagnosis and treatment of diminutive colorectal polyps

Cold polypectomy techniques for small and diminutive colorectal polyps: a systematic review and network meta-analysis of randomized controlled trials

OBJECTIVE

In the management of small and diminutive polyps, cold polypectomy is favored over electrocautery polypectomy. However, the optimal cold polypectomy technique is still controversial. Hence, this review aims to investigate the most effective cold technique for small and diminutive colorectal polyps.

METHODS

We conducted a systematic review and network meta-analysis synthesizing randomized controlled trials (RCTs) which were retrieved by systematically searching PubMed, EMBASE, Web of Science, SCOPUS, and Cochrane through 10 February 2023. R software, (R version 4.2.0) and meta-insight software were used to pool dichotomous outcomes using risk ratio (RR) presented with the corresponding confidence interval (CI). Our protocol was prospectively published in PROSPERO with ID: CRD42022345619.

RESULTS

Nineteen RCTs with 3649 patients and 4800 polyps were included in our analysis. Cold techniques (cold forceps polypectomy (CFP), jumbo forceps polypectomy (JFP), dedicated cold snare polypectomy (D-CSP), conventional cold snare polypectomy (C-CSP), underwater cold snare polypectomy (U-CSP), and cold snare endoscopic mucosal resection (CS-EMR) were included in our comparative analysis. CFP was less effective in achieving complete histological resection than C-CSP (RR: 1.10 with 95% CI [1.03-1.18]), CS-EMR (RR: 1.12 with 95% CI [1.02-1.23]), D-CSP (RR: 1.17 with 95% CI [1.04-1.32]), and U-CSP (RR: 1.21 with 95% CI [1.07-1.38]). However, the rest of the comparisons showed no difference.

CONCLUSION

CFP is the least effective method for small and diminutive polyps' removal, and any snare polypectomy technique will achieve better results, warranting more large-scale RCTs to investigate the most effective snare polypectomy technique.

Invasive Colon Cancer Inadvertently Resected by Cold Snare Polypectomy

A 74-year-old man with anemia underwent colonoscopy, which revealed a 4-mm polyp in the ascending colon. The polyp was subsequently diagnosed as an adenomatous lesion according to the narrow-band imaging (NBI) International Colorectal Endoscopic classification/Japan NBI Expert Team classification and resected via cold snare polypectomy (CSP). However, a pathological examination revealed a well-differentiated adenocarcinoma with a positive vertical margin. We performed additional endoscopic resection at the CSP scar area, revealing residual submucosal cancer with lymphatic involvement. The patient then underwent additional surgical resection. In such cases, additional endoscopic resection might be a treatment option.

Colonoscopic Polypectomy Preferences of Asian Endoscopists: Results of a Survey-Based Study

Background/Aims

The clinical practice pattern of polypectomy is not well-investigated in Asian countries. We aimed to survey Asian endoscopists about their preferred polypectomy techniques for given conditions and images of polyps.

Methods

A survey was performed using questionnaires composed of two parts a scenario-based questionnaire using scenarios of polyps, which were adopted from the European Society of Gastrointestinal Endoscopy guidelines, and an image-based questionnaire using provided endoscopic images of polyps.

Results

A total of 154 endoscopists participated in this survey. The most preferred resection techniques for diminutive (≤5 mm), small (6–9 mm), and benign-looking intermediate (10–19 mm) nonpedunculated polyps were cold forceps polypectomy, hot snare polypectomy, and endoscopic mucosal resection (EMR), respectively, in both the scenario- and image-based questionnaires. For benign-looking large (≥20 mm) nonpedunculated polyps, EMR and endoscopic submucosal dissection (ESD) were preferred in the scenario- and image-based surveys, respectively. In case of malignant nonpedunculated polyps, EMR and ESD were preferred for intermediate-sized and large lesions, respectively, according to the scenario-based survey. However, ESD was preferred in both intermediate-sized and large malignant nonpedunculated polyps according to the image-based survey. Trainee endoscopists, endoscopists working in referral centers, and endoscopists in the colorectal cancer–prevalent countries were independently associated with preference of cold snare polypectomy for removing small polyps.

Conclusions

The polypectomy practice patterns of Asian endoscopists vary, and cold snare polypectomy was not the most preferred resection method for polyps <10 mm in size, in contrast to recent guidelines. (Gut Liver 2021;15-400)

Histopathologic features and fragmentation of polyps with cold snare defect protrusions

BACKGROUND AND AIMS

Cold snare defect protrusions (CSDPs) include muscularis mucosa (MM) and submucosa tissue. CSDPs are thought to result from fragmentation of the specimen during shallow excision. Our aim in this study was to clarify whether CSDPs are associated with polyp fragmentation.

METHODS

We retrospectively analyzed 1026 neoplastic colorectal polyps resected by cold snare polypectomy for which the presence or absence of CSDPs was assessed from the endoscopic image. All prepared specimens were reviewed and assessed for the presence or absence of polyp fragmentation, and the proportion of MM on the stump was measured. In addition, the risk factors for CSDP occurrence were evaluated.

RESULTS

CSDPs occurred in 116 of the 1026 polyps (11.3%). Polyp fragmentation was significantly associated with the occurrence of CSDP on univariate analysis (odds ratio [OR], 3.74; P < .001) and multivariate analysis (OR, 3.13; P < .001). The proportion of MM >50% was significantly lower in the CSDP group than in the non-CSDP group (51.5% vs 70.9%, P < .001). CSDPs were significantly associated with a large polyp size (OR, 1.32; P = .007) and a large specimen size (OR, 1.24; P < .001) on multivariate analysis.

CONCLUSIONS

The occurrence of CSDP was associated with less MM on the stump and fragmentation of the specimen. Clinically, the presence of CSDP is a good indicator of polyp fragmentation.

Model construction of medical endoscope service evaluation system-based on the analysis of Delphi method

Background

Medical endoscope is widely used in clinical practice for the purpose of diagnosis and treatment, occupying around 5% of the medical device market. Evaluating the true service level of medical endoscope is essential and necessary to improve overall performance of medical diagnosis and treatment, and to maintain competitiveness of endoscope manufacturers, however, such a tool is not available in the market. This study develops an Evaluation Index System (EIS) to assess service level of medical endoscope, and to provide suggestions for improving the service level through the Delphi method.

Methods

Firstly, the possible factors influencing the service level were identified from literature review. In parallel, the Delphi expert method questionnaire was designed and 25 experts were invited to conduct three rounds of questionnaire, to evaluate and rate the possible factors. Finally, we determined the weights associated with the factors, using the analytic hierarchy process (AHP) and percentage method, and developed the service level EIS.

Results

The EIS consists of 3 first-level indicators, 24 s-level indicators and 68 third-level indicators. According to the weights computed using AHP, first-level indicators are ranked as post-sale (0.62), in-sale (0.25) and pre-sale (0.13). Through case verification, the medical endoscope brand Olympus had a total score of 4.17, Shanghai Aohua had a total score of 3.71, and Shanghai Chengyun had a total score of 3.28, which matches its market popularity and ranking in terms of market share. The results obtained from the EIS are consistent with the reality.

Conclusions

The EIS established in this study is comprehensive, reliable and reasonable with strong practicality. The EIS can act as a tool for the endoscope users to evaluate potential products and make informed choices. It also provides a measurable basis for endoscope manufacturers and service providers to improve service quality.

Endoscopic prediction of advanced histology in colorectal lesions sized <10 mm using the Japan Narrow-band imaging Expert Team classification

BACKGROUND AND AIM

Endoscopic diagnosis of advanced histology in colorectal lesions sized <10 mm is essential for appropriate selection of resection methods. The Japan Narrow-band imaging Expert Team (JNET) classification has been recently validated for the evaluation of colorectal lesions. Our objective was to investigate the diagnostic value of the JNET classification for advanced histology in colorectal lesions sized <10 mm.

METHODS

We enrolled 680 patients with 1472 colorectal lesions sized <10 mm diagnosed according to the JNET classification and who subsequently underwent endoscopic or surgical resection between January and December 2017. We retrospectively examined the relationship between the JNET findings and pathological histology. Multivariate analysis was carried out to assess the predictive power of the JNET findings and clinical characteristics of lesions.

RESULTS

Advanced histology was present in 29 (2.0%) lesions. Advanced histology was absent in 68 lesions diagnosed as JNET type 1, whereas 1389 lesions diagnosed as JNET type 2A included 19 lesions of advanced histology (1.4%) with high-grade dysplasia alone. Eleven lesions diagnosed as JNET type 2B comprised eight lesions of advanced histology (72.7%) with four high-grade dysplasia and four submucosal invasive cancer, and two lesions diagnosed as JNET type 3 were submucosal invasive cancer. Multivariate analysis showed that JNET type 2B + 3 was a stronger predictive factor for advanced histology than other clinical risk factors.

CONCLUSION

Narrow-band imaging with magnification according to the JNET classification may be a useful modality for identification of advanced histology in colorectal lesions sized <10 mm.

Management and risk factors for incomplete resection associated with jumbo forceps polypectomy for diminutive colorectal polyps: a single-institution retrospective study

BACKGROUND

Cold forceps polypectomy is simple and widely used in clinical practice. However, there are concerns about the risk of incomplete resection using this technique. In recent years, it has been reported that polypectomy with jumbo forceps (JF) is an effective treatment modality for diminutive polyps (DPs) because JF are able to remove large tissue samples with the combined advantage of a higher complete histological resection rate for DPs than standard forceps. To our knowledge, no studies have evaluated the risk factors for incomplete resection when polypectomy with JF is performed for DPs.

METHODS

From among 1129 DPs resected using JF at Hiroshima City Asa Citizens Hospital between November 2015 and December 2016, we retrospectively evaluated the clinical outcomes of 999 tumors with known histopathology and investigated the relationship between incomplete resection and clinicopathological factors.

RESULTS

Most lesions [985 (87%)] were low-grade dysplasia and 14 (1%) were high-grade dysplasia. The en bloc resection rate was 92% (918/999) and the histological en bloc resection rate was 78% (777/999). Multivariate analysis showed that the significant independent predictors of incomplete resection were tumor size ≥ 4 mm [odds ratio (OR) 3.8; 95% confidence interval (CI) 2.65-5.37; p < 0.01], non-tangential direction of forceps in relation to the tumor (OR 1.73; 95% CI 1.21-2.45; p < 0.01), and lack of muscularis mucosae in the pathological specimen (OR 15.7; 95% CI 9.16-27.7; p < 0.01).

CONCLUSIONS

This study identified significant independent predictors of incomplete resection of DPs which may be helpful when planning polypectomy with JF.

Challenges associated with the pathological diagnosis of colorectal tumors less than 10 mm in size

Various techniques including cold snare polypectomy and endoscopic mucosal resection are used for the removal of small colorectal polyps. Specimens of resected polyps are prepared in pathology laboratories and analyzed to make a pathological diagnosis. However, reports on how different resection methods influence the pathological diagnosis are limited. This article discusses the problems associated with the failure of polyp retrieval and fragmentation of small specimens during collection and the effects of certain parameters on the pathological diagnosis, particularly with regard to surgical margins. In the future, although pathologists are expected to encounter problems as a result of minor findings that are not clinically problematic, relatively rare cases such as submucosal invasion by a small carcinoma should not be overlooked.

Expression and location of IL-17A, E, F and their receptors in colorectal adenocarcinoma: Comparison with benign intestinal disease

The research aimed to investigate secretion, expression and location of IL-17 relative ligands, IL-17 relative receptors, infiltrating inflammatory cells and parenchymal structural cells in colorectal cancer (CRC) compared with ulcerative colitis (UC) and benign hyperplastic polyp. 29 human intestinal tissues with CRC, 17 with UC and 7 with polyp were stained using immunohistochemistry to evaluate immunoreactivity for IL-17 family relative ligands including IL-17A, E, F and their respective relative receptors such as IL-17RA, IL-17RB and IL-17RC. At the same time the infiltration of inflammatory cells including lymphocytes, phagocytes, mast cells and neutrophils and parenchymal structural cell changes involving vascular endothelial cells and CD90⁺ fibroblast cells were also evaluated using the same methods The immunoreactivity or positive inflammatory cells of all the sections were analyzed using professional image analysis software to determine statistical significance. The immunoreactivity for IL-17A, IL-17RA, IL-17E, IL-17RB and IL-17F showed significant decrease in CRC tissue when compared to UC (p = 0.00001. respectively). The reduction of above IL-17 relative ligands and receptors was accompanied by an obvious decrease in the number of infiltrating neutrophils and mast cells in CRC (p = 0.00001 and p = 0.007, respectively) but accompanied by a marked increase of CD31⁺ blood vessels (p = 0.001). The immunoreactivity of IL-17A, IL-17RA, IL-17E, IL-17RB and IL-17F and the numbers of infiltrating neutrophils and mast cells showed significant decrease in CRC tissues when compared to those in polyp (p < 0.05). In contrast, the immunoreactivity of IL-17RC and the numbers of CD3⁺ 1ymphocytes were elevated in CRC when compared with those in polyp (p = 0.0001, p = 0.007, respectively). In CRC tissues, positive correlations between IL-17A, IL-17RA with CD68⁺ macrophages were observed respectively (r = 0.621, p = 0.0001; r = 0.75, p = 0.0001). IL-17 cytokine family including ligands and their corresponding receptors were secreted and expressed by infiltrating inflammatory cells. Not only infiltrating lymphocytes but also increased blood endothelial cells were relative significantly to genesis and progression of CRC.

Polypectomy for complete endoscopic resection of small colorectal polyps

BACKGROUND AND AIMS

Small colorectal polyps are encountered frequently and may be incompletely removed during colonoscopy. The optimal technique for removal of small colorectal polyps is uncertain. The aim of this study was to compare the incomplete resection rate (IRR) by using EMR or cold snare polypectomy (CSP) for the removal of small adenomatous polyps.

METHODS

This was a prospective randomized controlled study from a tertiary-care referral center. A total of 358 patients who satisfied the inclusion criteria (polyp sized 6-9 mm) were randomized to the EMR (n =179) and CSP (n =179) groups, and their polyps were treated with conventional EMR or CSP, respectively. After polypectomy, an additional 5 forceps biopsies were performed at the base and margins of polypectomy sites to assess the presence of residual polyp tissue. The EMR and CSP samples were compared to assess the IRR.

RESULTS

Among a total of 525 polyps, 415 (79.0%) were adenomatous polyps, and 41 (16.4%) were advanced adenomas. The overall IRR for adenomatous polyps was significantly higher in the CSP group compared with the EMR group (18/212, 8.5% vs 3/203, 1.5%; P = .001). Logistic regression analysis revealed that the CSP procedure was a stronger risk factor for the IRR (odds ratio [OR] 6.924; 95% confidence interval [CI], 2.098-24.393; P = .003). In addition, piecemeal resection was the most important risk factor for the IRR (OR 28.696; 95% CI, 3.620-227.497; P = .001). The mean procedure time for polypectomy was not significantly different between the EMR and CSP groups (5.5 ± 2.7 vs 4.7 ± 3.4 minutes; P = .410). None of these patients presented with delayed bleeding. There were no severe adverse events related to the biopsies.

CONCLUSIONS

EMR was significantly superior to CSP for achieving complete endoscopic resection of small colorectal polyps. Patients with piecemeal resection of polyps had a higher risk for incomplete resection. (Clinical trial registration number: Hongwei-1102-12.).

Clinical impact of surveillance colonoscopy using magnification without diminutive polyp removal

BACKGROUND AND AIM

In Western countries, endoscopic removal of all adenomas during colonoscopy is recommended. The present study evaluates the usefulness of magnifying colonoscopy without removal of diminutive (≤5 mm) colorectal polyps.

METHODS

Patients with diminutive polyps who were observed for over 5 years using magnification at Hiroshima University Hospital were selected retrospectively. Lesions ≥6 mm in size, depressed lesions, and lesions with type V pit pattern were indications for endoscopic resection. We investigated the characteristics of lesions indicated for endoscopic resection detected on surveillance colonoscopy and the risk factors for the incidence of lesions indicated for endoscopic resection.

RESULTS

A total of 706 consecutive patients were enrolled. Sixty-eight lesions indicated for endoscopic resection were detected, averaging 9.0 ± 4.8 mm, and 33 (49%) lesions were located in the right colon. Pathological diagnoses were adenoma, Tis carcinoma, and T1 carcinoma in 58 (85%), eight (12%), and two (3%) lesions, respectively. Five lesions were considered to grow from previously detected diminutive polyps. Relative risks for the incidence of a lesion indicated for endoscopic resection were 1.76 (95% confidence interval [CI], 1.004-3.23) for males compared with females, 3.76 (95% CI, 2.03-7.50) for more than three polyps at initial colonoscopy compared with one polyp, and 2.84 (95% CI, 1.43-5.24) for patients with carcinoma at initial colonoscopy compared with patients with no lesion indicated for endoscopic resection. Nine carcinomas were resected endoscopically.

CONCLUSION

Diminutive low-grade adenomas detected by using magnifying colonoscopy may not necessarily require removal.

Comparative efficacy of cold polypectomy techniques for diminutive colorectal polyps: a systematic review and network meta-analysis

BACKGROUND

Although cold polypectomy techniques are preferred over polypectomy with electrocautery in the management of diminutive polyps, comprehensive comparisons among various cold polypectomy techniques have not yet been fully performed.

METHODS

We searched for all relevant randomized controlled trials published up until October 2016 examining the efficacy of cold polypectomy techniques for diminutive polyps. Cold polypectomy techniques were classified as cold forceps polypectomy (CFP), jumbo forceps polypectomy (JFP), traditional cold snare polypectomy (CSP), and dedicated CSP, according to the type of device. A network meta-analysis was performed to calculate the direct and indirect estimates of efficacy among the cold polypectomy techniques.

RESULTS

Seven studies with 703 patients and 968 polyps were included in the meta-analysis. Regarding comparative efficacy for complete histological eradication, there was no inconsistency in the network (Cochran's Q test, df = 4, P = 0.22; I ² = 30%). In terms of complete histological eradication, both dedicated and traditional CSP were superior to CFP (odds ratio [OR] [95% confidence interval [CI]] 4.31 [1.92-9.66] and 2.45 [1.30-4.63], respectively); dedicated CSP was superior to traditional CSP (OR [95% CI] 1.76 [1.07-2.89]); and there was no difference between JFP versus CFP (OR [95% CI] 1.36 [0.40-4.61]). Regarding tissue retrieval rate, there was no difference between dedicated versus traditional CSP (OR [95% CI] 1.03 [0.44-2.38]). The procedure time for CSP was comparable to that of CFP.

CONCLUSIONS

Dedicated CSP was shown to be superior to other cold polypectomy techniques in terms of complete histological eradication. Cold polypectomy using a dedicated snare can be recommended for the removal of diminutive colorectal polyps.

The concept of 'Semi-clean colon' using the pit pattern classification system has the potential to be acceptable in combination with a <3-year surveillance colonoscopy

Histological features of colorectal lesions are currently evaluated via a magnifying chromoendoscopy [pit pattern (PIT) classification]. Advanced histological features are rarely observed in diminutive (≤5 mm) adenomatous polyps (DAPs). The Japanese guidelines indicate that diminutive neoplastic lesions without carcinomatous findings may be left untreated and followed up. At the present institution, DAPs with type IIIL PIT are left untreated in various cases, whereas lesions with type III, IV or V PIT are typically resected via routine colonoscopy. This retrospective study aimed to assess the management of DAPs using PIT classification. The participants of the study included patients <30 years previously referred for an initial colonoscopy, then reobserved for <3 years following the procedure. Participants were classified into three groups: Group A, Patients with type IIIL PIT DAP left untreated (semi-clean colon group); group B, patients with all neoplastic polyps, including DAPs, resected (clean colon group); and group C, patients without any adenomatous polyps (internal control group). The cumulative incidence of the index lesions (ILs) at the follow-up colonoscopy was analysed among the three groups. A total of 4,313 patients were enrolled in the study, with categorization as follows: Group A, 1,246; group B, 1,205; and group C, 1,862 patients. ILs were detected in group A, 100 (8.0%); group B, 104 (8.6%); and group C, 29 (1.6%) patients. There was no significant difference observed between groups A and B. It was verified that removing the type IIIL PIT DAPs did not decrease the incidence of ILs within a 3-year time period. Therefore, these polyps may be left untreated in combination with patient reobservation at an appropriate time interval, potentially one equal to that suggested following a polypectomy.

Clinical, endoscopic and pathological characteristics of colorectal polyps in elderly patients: Single-center experience

Increasing age is a risk factor for the development of colorectal adenomas and advanced adenomas. However, few studies have been published on the features of colorectal polyps in the elderly. The present study aimed to investigate the clinical, enteroscopic and pathological characteristics of colorectal polyps in Chinese elderly patients in a single center (The Central Hospital of Wuhan, Hubei, China). The endoscopic and pathological reports of colonoscopies performed in our center were retrospectively analyzed. A total of 7,795 consecutive patients referred for colonoscopy were evaluated between January 2013 and December 2014. Of the 297 who met the inclusion criteria, 279 polyps were observed in men and 230 in women. Of all the polyps, 263 were non-adenomatous polyps, 104 were non-advanced adenomas and 142 were advanced adenomas. 336 polyps were left-sided and 173 were right-sided. Polyps ≥10 mm were more likely to exhibit an adenomatous component and advanced features, and these findings continued to hold true when the size cut-off was set at 5 mm. The data shown in the present study have revealed that a significant number of polyps lie proximal to the splenic flexure. Thus, evaluation of the whole bowel is particularly important in elderly patients who are undergoing colonoscopy. In addition, the polyp size was associated with the presence of adenoma, and advanced component, diminutive and small polyps should not be ignored in elderly patients.

Resection of Diminutive and Small Colorectal Polyps: What Is the Optimal Technique?

Colorectal polyps are classified as neoplastic or non-neoplastic on the basis of malignant potential. All neoplastic polyps should be completely removed because both the incidence of colorectal cancer and the mortality of colorectal cancer patients have been found to be strongly correlated with incomplete polypectomy. The majority of colorectal polyps discovered on diagnostic colonoscopy are diminutive and small polyps; therefore, complete resection of these polyps is very important. However, there is no consensus on a method to remove diminutive and small polyps, and various techniques have been adopted based on physician preference. The aim of this article was to review the diverse techniques used to remove diminutive and small polyps and to suggest which technique will be the most effective.

Aberrant Gene Expression Profile of Unaffected Colon Mucosa from Patients with Unifocal Colon Polyp

Background

The aim of this study was to evaluate gene expression profiles in unaffected colon mucosa and polyp tissue from patients with unifocal colon polyp to investigate the potential mucosa impairment in normal-appearing colon mucosa from these patients.

Material/Methods

Colon polyp patients were prospectively recruited. We obtained colon biopsies from the normal-appearing sites and polyp tissue through colonoscopy. Gene expression analysis was performed using microarrays. Gene ontology and clustering were evaluated by bioinformatics.

Results

We detected a total of 711 genes (274 up-regulated and 437 down-regulated) in polyp tissue and 256 genes (170 up-regulated and 86 down-regulated) in normal-appearing colon mucosa, with at least a 3-fold of change compared to healthy controls. Heatmapping of the gene expression showed similar gene alteration patterns between unaffected colon mucosa and polyp tissue. Gene ontology analyses confirmed the overlapped molecular functions and pathways of altered gene expression between unaffected colon mucosa and polyp tissue from patients with unifocal colon polyp. The most significantly altered genes in normal-appearing tissues in polyp patients include immune response, external side of plasma membrane, nucleus, and cellular response to zinc ion.

Conclusions

Significant gene expression alterations exist in unaffected colon mucosa from patients with unifocal colon polyp. Unaffected colon mucosa and polyp tissue share great similarity and overlapping of altered gene expression profiles, indicating the potential possibility of recurrence of colon polyps due to underlying molecular abnormalities of colon mucosa in these patients.

Feasibility of cold snare polypectomy in Japan: A pilot study

AIM: To investigate the feasibility of cold snare polypectomy (CSP) in Japan.

METHODS: The outcomes of 234 non-pedunculated polyps smaller than 10 mm in 61 patients who underwent CSP in a Japanese referral center were retrospectively analyzed. The cold snare polypectomies were performed by nine endoscopists with no prior experience in CSP using an electrosurgical snare without electrocautery.

RESULTS: CSPs were completed for 232 of the 234 polyps. Two (0.9%) polyps could not be removed without electrocautery. Immediate postpolypectomy bleeding requiring endoscopic hemostasis occurred in eight lesions (3.4%; 95%CI: 1.1%-5.8%), but all were easily managed. The incidence of immediate bleeding after CSP for small polyps (6-9 mm) was significantly higher than that of diminutive polyps (≤ 5 mm; 15% vs 1%, respectively). Three (5%) patients complained of minor bleeding after the procedure but required no intervention. The incidence of delayed bleeding requiring endoscopic intervention was 0.0% (95%CI: 0.0%-1.7%). In total, 12% of the resected lesions could not be retrieved for pathological examination. Tumor involvement in the lateral margin could not be histologically assessed in 70 (40%) lesions.

CONCLUSION: CSP is feasible in Japan. However, immediate bleeding, retrieval failure and uncertain assessment of the lateral tumor margin should not be underestimated. Careful endoscopic diagnosis before and evaluation of the tumor residue after CSP are recommended when implementing CSP in Japan.