Outline of Japanese Guidelines for Colorectal Endoscopic Submucosal Dissection and Endoscopic Mucosal Resection with a Short Reference to the Western Recommendations

The Japan Gastroenterological Endoscopy Society published the latest English versions of the guidelines for endoscopic submucosal dissection and endoscopic mucosal resection for colorectal neoplastic lesions and colorectal cold polypectomy in 2020 and 2022, respectively. In this article, I present a comprehensive overview of these guidelines, including a comparison with the Western recommendations.

Guidelines for Colorectal Cold Polypectomy (supplement to "Guidelines for Colorectal Endoscopic Submucosal Dissection/Endoscopic Mucosal Resection")

The Japan Gastroenterological Endoscopy Society published the second edition of the "Guidelines for Colorectal Endoscopic Submucosal Dissection/Endoscopic Mucosal Resection" in 2019 to clarify the indications for colorectal endoscopic mucosal resection (EMR) and endoscopic submucosal dissection and to ensure appropriate preoperative diagnoses as well as effective and safe endoscopic treatment in front-line clinical settings. Endoscopic resection with electrocautery, including polypectomy and EMR, is indicated for colorectal polyps. Recently, the number of facilities introducing and implementing cold polypectomy without electrocautery has increased. Herein, we establish supplementary guidelines for cold polypectomy. Considering that the level of evidence for each statement is limited, these supplementary guidelines must be verified in clinical practice.

Underwater cold snare polypectomy for colorectal adenomas

BACKGROUND AND AIM

Cold snare polypectomy (CSP) is a safe treatment for colorectal adenomas. However, the R0 resection rate is not sufficiently high because of inadequate resection of muscularis mucosa. We hypothesized that CSP in an underwater environment could improve this procedure by helping to safely achieve resection containing the muscularis mucosa. We have named this procedure underwater cold snare polypectomy (UCSP). We aimed to investigate the efficacy and safety of UCSP for colorectal adenomas.

METHODS

Between May 2017 and April 2018, patients diagnosed with colorectal adenomas <9 mm underwent UCSP. After follow-up colonoscopy 3 weeks later, the patients post-UCSP scars were biopsied. Outcomes were compared with those of a historical control group who underwent conventional CSP in our previous study using propensity score-matching methods.

RESULTS

Overall, 224 lesions in 65 patients were prospectively resected by UCSP. Pathologically, 209 lesions were adenomas (4.5 ± 1.5 mm) including one intramucosal carcinoma. Only one pathological residual adenoma was identified, but there was no significant difference in the residual rate between the UCSP and CSP groups (both 1.0%). No complications were observed. R0 resection rate and rate of area containing the muscularis mucosa in the UCSP group were significantly higher than those in the CSP group (80.2% vs 32.7%, P < 0.001; 50.0% vs 35.3%, P = 0.015).

CONCLUSION

Underwater cold snare polypectomy for diminutive and small colorectal adenomas was safe and effective from the perspective of pathological complete resection, which is likely facilitated by achieving an adequate depth of resection.

Safety and efficacy of cold polypectomy compared to endoscopic mucosal resection and hot biopsy polypectomy

Backgrounds: Recently, several studies have demonstrated the usefulness of cold polypectomy (CP), a safe and simple method for the removal of small polyps. We investigated the safety and efficacy of CP compared to that of endoscopic mucosal resection (EMR) and hot biopsy polypectomy (HB). Methods: We retrospectively examined 1713 colorectal polyps (size 1-9 mm) in 731 patients. CP, EMR, and HB were performed on 476, 997, and 240 lesions, respectively. We compared the region, size, morphology, the presence of delayed bleeding as overt bleeding 24 h after operation, number of clips, pathology, the presence of antithrombotic therapy, procedure time from detection of a polyp to resection and hemostasis, device cost including device and clips, and polyp remnants. Results: The delayed bleeding in the CP group (0/476) was significantly lower compared to that in the HB group (3/240) and EMR group (7/997). There were no cases of perforations. The procedure time was significantly shorter in the CP group than in the EMR group (91.3sec vs 290.1sec, p < .0001). The CP group had a significantly lower device cost than the HB and EMR groups (49.2USD vs 58.0 USD vs 91.3 USD, p < .0001) was not inferior in terms of polyp remnants to the EMR and HB groups. (1.4% vs 0.6% vs 6.1%, p = .1599) Conclusions: CP is a safe treatment that achieves less delayed bleeding. Moreover, CP is not inferior to other groups in terms of polyp remnants and offers a cost benefit. CP can be considered useful for colonic polypectomy.

Usefulness of close observation with non-magnified blue laser imaging for determining cold polypectomy indications

PURPOSE

To examine the usefulness of non-magnified close observation with blue laser imaging (BLI) using a colonoscope with close observation capability in determining indications for cold polypectomy.

METHODS

We conducted an image evaluation study on 100 consecutive colorectal lesions of 10 mm or less which were observed endoscopically without magnification using BLI mode prior to treatment. Two experts and two non-experts reviewed the images using the Japan NBI expert team (JNET) classification and the diagnostic accuracy was analyzed.

RESULTS

The final pathological diagnoses of the 100 lesions were hyperplastic/sessile serrated polyp (HP/SSP), low grade dysplasia (LGD), high grade dysplasia (HGD) and deep submucosal invasive cancer (dSM), respectively, in 12, 79, 9 and 0 lesions. When JNET classification type 1 corresponds to HP/SSP; 2A to LGD; 2B to HGD; and 3 to dSM; the overall diagnostic accuracy was 84.3%. Accuracy was 90.5% for experts and 78.0% for non-experts. High confidence rate was 67.5% for experts and 48.0% for non-experts. In diagnostic accuracy for HGD, the sensitivity, specificity, PPV and NPV were, respectively, 77.8%, 98.9%, 87.5% and 97.8% for experts; and 66.6%, 92.3%, 46.2% and 96.6% for non-experts.

CONCLUSIONS

The diagnostic accuracy of unmagnified close observation with BLI using a colonoscope with close observation capability is similar to that reported for magnifying endoscopy and is useful in predicting the histological diagnosis of colorectal polyps of 10 mm or less although the effectiveness may be limited for non-experts. This modality is a potentially useful tool in deciding indications for cold polypectomy.

Histological outcomes between hot and cold snare polypectomy for small colorectal polyps

BACKGROUND/AIM

To compare the complete resection rate of hot and cold snare polypectomy for small colorectal polyps.

PATIENTS AND METHODS

We retrospectively reviewed the medical records of 233 consecutive patients with 461 colorectal polyps up to 10 mm in diameter that were treated by hot or cold snare polypectomy between April 2014 and August 2016. Lesions treated by hot snare polypectomy (n = 137) and cold snare polypectomy (n = 324) were compared. The histological complete resection rates were evaluated between the two groups. We analyzed the relationship between factors for complete resection and clinical factors using multivariate analysis.

RESULTS

There was a significantly higher complete resection rate in hot snare polypectomy than in cold snare polypectomy (70.5% vs. 47.3%; P < 0.001). In the analysis of subgroups categorized according to polyp size, the complete resection rate for hot snare polypectomy was significantly higher than that for cold snare polypectomy among polyps ≥6 mm (69.0% vs. 43.5%; P < 0.001). Among polyps ≤5 mm, no significant difference regarding the complete resection rate was observed between the methods (81.3% vs. 53.4%; P = 0.057). There was no significant difference in the incidence of adverse events between the two groups. Multivariate analysis revealed that using hot snare polypectomy (odds ratio 3.03; P < 0.001), small lesion size (odds ratio 1.57; P = 0.049), and lesion location in the left colon (odds ratio 1.73; P = 0.007) were independent factors for complete resection.

CONCLUSION

Hot snare polypectomy provides a higher complete resection rate than does cold snare polypectomy for larger (6-10 mm) subcentimeter colorectal polyps.

Advances in the removal of diminutive colorectal polyps

Diminutive polyps (<5 mm in diameter) represent the majority of polyps found during colonoscopy; about a half of them are adenomatous, with low risk of advanced neoplasia. Recent studies have demonstrated that cold polypectomy should be considered the recommended approach for resecting diminutive polyps and that cold snaring may be superior to cold forceps biopsy, at least for polyps of 4-5 mm. Recently, electronic chromoendoscopy has been applied to characterization of diminutive polyps to discriminate adenomatous from nonadenomatous lesions. Optical diagnosis of polyp histology could potentially exert huge cost savings by the 'resect and discard' strategy for diminutive polyps and 'leaving-in' for diminutive hyperplastic polyps in the recto-sigmoid colon. These policies represent the mainstay for adopting endoscopy-directed post-polypectomy surveillance strategies, endorsed by both American and European Endoscopy Societies. Accuracy of both histology and surveillance intervals predictions from academic centers have been encouraging, although the same performance has not been replicated in community practices.

Cold polypectomy techniques for diminutive polyps in the colorectum

Adequate colonoscopic polypectomy is a very important intervention for the prevention of colorectal cancer progression during screening and surveillance colonoscopy. Whereas various techniques are used for the removal of diminutive polyps, including cold biopsy forceps, hot biopsy forceps, hot snare, and cold snare, hot polypectomy techniques with electrocautery have been associated with an increased risk of electrocautery-related complications, including immediate and/or delayed bleeding or perforation. In contrast, recent studies have found a polypectomy technique without electrocautery, so-called cold polypectomy, to be a safer and more efficacious technique. The present article discusses the use of cold polypectomy techniques and describes how cold biopsy forceps polypectomy using jumbo biopsy forceps designed with a greater capacity for removing larger tissue samples, and cold snare polypectomy, are adequate for removing diminutive polyps completely and safely and shorten withdrawal time of the colonoscopy procedure.