Colorectal endoscopic submucosal dissection from a Western perspective: Today’s promises and future challenges

Rectal neuroendocrine tumours and the role of emerging endoscopic techniques

Rectal neuroendocrine tumours represent a rare colorectal tumour with a 10 fold increased prevalence due to incidental detection in the era of colorectal screening. Patient outcomes with early diagnosis are excellent. However endoscopic recognition of this lesion is variable and misdiagnosis can result in suboptimal endoscopic resection with subsequent uncertainty in relation to optimal long-term management. Endoscopic techniques have shown particular utility in managing this under-recognized neuroendocrine tumour.

Prediction of lymph node metastasis in early colorectal cancer based on histologic images by artificial intelligence

Risk evaluation of lymph node metastasis (LNM) for endoscopically resected submucosal invasive (T1) colorectal cancers (CRC) is critical for determining therapeutic strategies, but interobserver variability for histologic evaluation remains a major problem. To address this issue, we developed a machine-learning model for predicting LNM of T1 CRC without histologic assessment. A total of 783 consecutive T1 CRC cases were randomly split into 548 training and 235 validation cases. First, we trained convolutional neural networks (CNN) to extract cancer tile images from whole-slide images, then re-labeled these cancer tiles with LNM status for re-training. Statistical parameters of the tile images based on the probability of primary endpoints were assembled to predict LNM in cases with a random forest algorithm, and defined its predictive value as random forest score. We evaluated the performance of case-based prediction models for both training and validation datasets with area under the receiver operating characteristic curves (AUC). The accuracy for classifying cancer tiles was 0.980. Among cancer tiles, the accuracy for classifying tiles that were LNM-positive or LNM-negative was 0.740. The AUCs of the prediction models in the training and validation sets were 0.971 and 0.760, respectively. CNN judged the LNM probability by considering histologic tumor grade.

Snare Tip Is an Alternative Tool for Colorectal Endoscopic Submucosal Dissection

BACKGROUND

Colorectal endoscopic submucosal dissection is typically performed by specialized knife, such as a dual knife. However, it is not covered by Taiwan's National Health Insurance. In the literature review, using a traditional snare tip for endoscopic submucosal dissection has been reported for stomach lesions only.

OBJECTIVE

The purpose of this study was to evaluate the outcomes of colorectal endoscopic submucosal dissection using a snare tip.

DESIGN

We retrospectively reviewed the clinical using of a snare tip compared with a dual knife for colorectal endoscopic submucosal dissection. Postoperative short- and long-term outcomes were investigated after the procedure.

SETTINGS

This study was conducted at a single tertiary care institution.

PATIENTS

Patients who could not afford the expense of a specialized knife were included.

MAIN OUTCOME MEASURES

Dissection time, dissection speed, and perioperative complications were used for short-term outcome measurement. Recurrence-free rate was used for long-term outcome measurement.

RESULTS

Twenty-one lesions were in the snare tip group and 57 lesions in the dual knife group. The outcomes, including rate of en bloc resection, complication, local recurrence, and recurrence-free interval, between the 2 groups were similar. The mean resected specimen diameter in the dual knife group is larger than the snare tip group (p = 0.041). The dissection time of the snare tip group was shorter than the dual knife group (p = 0.025). However, the dissection speed was significantly slower in the snare tip group than in the dual knife group (p = 0.008).

LIMITATIONS

This study was a retrospective and single doctor chart review in nature with a limited patient number.

CONCLUSIONS

The snare tip is an alternative tool for colorectal endoscopic submucosal dissection in a selected population without the support of specialized knives, such as the dual knife. Although the dissection speed is slower using a snare tip, it is still a recommended technique for developing country or low-income patients.

Feasibility and learning curve of unsupervised colorectal endoscopic submucosal hydrodissection at a Western Center

OBJECTIVES

Colorectal endoscopic submucosal dissection (CR-ESD) is an evolving technique in Western countries. We aimed to determine the results of the untutored implementation of endoscopic submucosal hydrodissection for the treatment of complex colorectal polyps and establish the learning curve for this technique.

METHODS

This study included data from 80 consecutive CR-ESDs performed by a single unsupervised western therapeutic endoscopist. To assess the learning curve, procedures were divided into four groups of 20 each.

RESULTS

En bloc resection was achieved in 55, 75, 75 and 95% cases in the consecutive time periods (period 1 vs. 4, P = 0.003). Curative resection was achieved in 55, 75, 70 and 95%, respectively (P = 0.037). Overall, series results demonstrated R0 resection in 75% of cases, with 23.7% requiring conversion to endoscopic piecemeal mucosal resection, and 1.25% incomplete resections. Complications included perforations (7.5%) and bleeding (3.7%). Multivariate analysis revealed factors more likely to result in association with non en bloc vs. En bloc resection, where polyp size ≥35 mm [70 vs. 23.4%; odds ratio (OR) 13.2 (1.7-100.9); P = 0. 013], severe fibrosis [40 vs. 11.7%; OR 10.2 (1.2-86.3); P = 0.033] and where carbon dioxide for insufflation was not used [65 vs. 30%; OR 0.09 (0.01-0.53); P = 0.008].

CONCLUSION

CR-ESD by hydrodissection has good safety and efficacy profile and offers well tolerated and effective treatment for complex polyps. As such, this technique may be useful in the West, in centers, where previous gastric ESD is not frequent or Japanese mentoring is not possible.

Task Deconstruction of Colonic Endoscopic Submucosal Dissection (cESD): An Expert Consensus

BACKGROUND

Slow adoption of colonic ESD (cESD) in the US is multifactorial due to: lack of clinical training construct (e.g., gastric ESD in Japan), complication risks, and technical difficulty. More than 28,000 patients/year undergo colonic resection for benign lesions that could be managed effectively with cESD. Selected patients could avoid surgery if procedural adoption of cESD increased due to more accessible training. Current US cESD training is scarce, and existing programs are piecemeal. There is a need to develop an effective national training program for practicing endoscopists. A prerequisite to training development is a comprehensive task list delineating procedural steps. The aim of this work was to describe an evidence-based method of deconstructing cESD into the essential steps to provide a task list to guide teaching and assessment.

METHODS

Subject-matter experts (SMEs) performed a literature review to create an initial procedural step list. Eleven clinical cESD SMEs and four educational SMEs formed a 'cESD Working Group' to develop consensus regarding steps. Through a two-stage modified Delphi process, a consensus on a comprehensive standard cESD deconstructed task list was reached. The aim was to standardize cESD teaching to efficiently bring a novice to safe performance.

RESULTS

A literature review identified eight initial cESD steps. First-round Delphi consensus was gained on seven steps. Semi-structured focus group discussions resulted in consensus on a modified version of 7 of the initial steps, with addition of two steps. Consensus on procedural actions needed to perform each step was achieved after the hands-on laboratory. The final result was a ten-step deconstructed task list for standard cESD.

CONCLUSION

The development of a standardized cESD procedural task list provides a foundation to safely and efficiently teach cESD to practicing endoscopists. This list can be used to develop a training pathway to increase procedural adoption. Selected patients currently undergoing colonic resections could benefit from increased adoption of cESD.

Prediction of early colorectal cancer metastasis by machine learning using digital slide images

BACKGROUND AND OBJECTIVES

Prediction of lymph node metastasis (LNM) for early colorectal cancer (CRC) is critical for determining treatment strategies after endoscopic resection. Some histologic parameters for predicting LNM have been established, but evaluator error and inter-observer disagreement are unsolved issues. Here we describe an LNM prediction algorithm for submucosal invasive (T1) CRC based on machine learning.

METHODS

We conducted a retrospective single-institution study of 397 T1 CRCs. Several morphologic parameters were extracted from whole slide images of cytokeratin immunohistochemistry using Image J. A random forest algorithm for a training dataset (n = 277) was executed and used to predict LNM for the test dataset (n = 120). The results were compared with conventional histologic evaluation of hematoxylin-eosin staining.

RESULTS

Machine learning showed better LNM predictive ability than the conventional method on some datasets. Cross validation revealed no significant difference between the methods. Machine learning resulted in fewer false-negative cases than the conventional method.

CONCLUSIONS

Machine learning on whole slide images is a potential alternative for determining treatment strategies for T1 CRC.

Efficacy and safety of endoscopic submucosal dissection for non-ampullary duodenal polyps: A systematic review and meta-analysis

BACKGROUND AND AIMS

Endoscopic submucosal dissection (ESD) is commonly used to treat early-stage digestive cancer because it results in a higher frequency of en-bloc resection and a lower frequency of local recurrence. However, the efficacy and safety of duodenal ESD remain unclear. Therefore, present study is aimed at evaluating clinical outcomes of duodenal ESD.

METHODS

To evaluate the efficacy and safety of duodenal ESD, electronic databases (MEDLINE, CENTRAL and EMBASE) were searched by two independent reviewers. The authors were contacted for additional information. A meta-analysis was performed to evaluate the efficacy and safety of duodenal ESD.

RESULTS

A total of 7 studies (203 patients) were included in the quantitative synthesis analysis. The pooled proportions of the frequencies of en-bloc resection, need for surgical intervention, bleeding, intraoperative perforation and delayed perforation were 87%, 4%, 2%, 15% and 2%, respectively. The quality of evidence regarding on surgical intervention outcomes was rated as moderate, whereas that of en-bloc resection was rated as low because of its marked inconsistency.

CONCLUSIONS

Duodenal ESD produced acceptable outcomes in terms of the en-bloc R0 resection, but the incidence of procedure-related adverse events is high (PROSPERO register, CRD42017057110).

Immunohistochemical evaluation of tumor budding for stratifying T1 colorectal cancer: optimal cut-off value and a novel computer-assisted semiautomatic method

High-grade tumor budding is an adverse prognostic factor for submucosal invasive (T1) colorectal cancer used to predict the risk for lymph node metastasis in endoscopically resected specimens. Cytokeratin immunohistochemistry is a potential option for evaluating tumor budding. The optimal cut-off value between low- and high-grade budding has not yet been determined, however, and the high inter-observer variability in selecting budding foci remains problematic. We explored the optimal cut-off value for predicting lymph node metastasis using cytokeratin immunohistochemistry, and developed a novel computer-assisted semiautomatic quantification method to reduce inter-observer variability. A retrospective single-institution study of 463 T1 colorectal cancer cases was conducted. Cases were split into derivation and validation datasets. Tumor budding foci were counted manually and semiautomatically using Image J software on cytokeratin immunohistochemistry-stained specimens. We determined the cut-off values and compared inter-observer variability among pathologists between the two methods. Univariate and multivariate analyses of the derivation dataset were performed to select the risk factors for lymph node metastasis. Predictive simulation for the validation dataset was conducted. The optimal cut-off values for the manual and semiautomatic methods were ≥10 and ≥12, respectively. For both methods, multivariate analyses revealed that venous invasion, lymphatic invasion, and high-grade tumor budding were independent risk factors for lymph node metastasis. The semiautomatic method provided significantly better inter-observer agreement. The predictive and observed lymph node metastasis frequencies were highly correlated in the validation dataset.

Modular laser-based endoluminal ablation of the gastrointestinal tract: in vivo dose-effect evaluation and predictive numerical model

BACKGROUND

Endoscopic submucosal dissection allows for "en bloc" removal of early gastrointestinal neoplasms. However, it is technically demanding and time-consuming. Alternatives could rely on energy-based techniques. We aimed to evaluate a predictive numerical model of thermal damage to preoperatively define optimal laser settings allowing for a controlled ablation down to the submucosa, and the ability of confocal endomicroscopy to provide damage information.

MATERIALS AND METHODS

A Nd:YAG laser was applied onto the gastric mucosa of 21 Wistar rats on 10 spots (total 210). Power settings ranging from 0.5 to 2.5W were applied during 1-12 s, with a consequent energy delivery varying from 0.5 to 30 J. Out of the 210 samples, a total of 1050 hematoxilin-eosin stained slides were obtained. To evaluate thermal injury, the ratio between the damage depth (DD) over the mucosa and the submucosa thickness (T) was calculated. Effective and safe ablation was considered for a DD/T ratio ≤ 1 (only mucosal and submucosal damage). Confocal endomicroscopy was performed before and after ablation. A numerical model, using human physical properties, was developed to predict thermal damage.

RESULTS

No full-thickness perforations were detected. On histology, the DD/T ratio at 0.5 J was 0.57 ± 0.21, significantly lower when compared to energies ranging from 15 J (a DD/T ratio = 1.2 ± 0.3; p < 0.001) until 30 J (a DD/T ratio = 1.33 ± 0.31; p < 0.001). Safe mucosal and submucosal ablations were achieved applying energy between 4 and 12 J, never impairing the muscularis propria. Confocal endomicroscopy showed a distorted gland architecture. The predicted damage depth demonstrated a significant positive linear correlation with the experimental data (Pearson's r 0.85; 95% CI 0.66-0.94).

CONCLUSIONS

Low-power settings achieved effective and safe mucosal and submucosal ablation. The numerical model allowed for an accurate prediction of the ablated layers. Confocal endomicroscopy provided real-time thermal damage visualization. Further studies on larger animal models are required.

Implementation of mentor-assisted colorectal endoscopic submucosal dissection in Sweden; learning curve and clinical outcomes

OBJECTIVE

It's still challenging to introduce colorectal (CR) ESD in Western countries. We assessed the feasibility of introducing and implementing CR-ESD in Sweden with hiring Japanese expert as a supervisor.

METHODS

We analyzed 71 consecutive CR-ESD cases performed by two endoscopists who had no (endoscopist A (E-A)) or 20 cases (endoscopist B (E-B)) of experience in ESD. E-A performed rectal lesions while E-B performed lesions in any locations. Factors associated with failure in en bloc resection and in self-accomplishment were analyzed.

RESULTS

Overall en bloc and R0 resection rates were 80.3% and 70.4%. Adverse event occurred in 7.0% including two perforations, two post-operative hemorrhage and one delayed perforation. Only case with delayed perforation underwent surgical treatment. Total self-accomplishment rate was 50% (10/20) for E-A, and 37.3% (19/51) for E-B. Dividing each performer's cases into three learning phases, self-accomplishment rates increased from 42.9% to 83.3% for E-A, and from 29.4% to 70.6% for E-B, as well as en bloc resection rates from 71.4% to 100% for E-A, and from 52.9% to 94.1% for E-B. Multivariate analysis revealed that location upper than rectum, lesions with formerly taken biopsy and lesions larger than 30mm were significantly associated with en bloc resection failure.

CONCLUSIONS

Implementation of CR-ESD with hiring Japanese supervisor for certain period was safe for patients and effective for good learning curve.

Comparison of guidelines for the management of rectal cancer

A comparison between NCCN, ESMO and JSCCR Guidelines is presented, concerning the treatment of rectal cancer, with an analysis and discussion of their discrepancies. Differences indicate areas for research.

Using Endoscopic Submucosal Dissection as a Routine Component of the Standard Treatment Strategy for Large and Complex Colorectal Lesions in a Western Tertiary Referral Unit

BACKGROUND

Colorectal endoscopic submucosal dissection results in high rates of en bloc resection, few recurrences, and accurate diagnosis, and it is useful in lesions with significant fibrosis. However, endoscopic submucosal dissection has not been widely adopted by Western endoscopists and the published experience from Western centers is very limited.

OBJECTIVES

This study aims to report the outcomes from a UK tertiary center using colorectal endoscopic submucosal dissection as part of a standard lesion specific treatment approach.

DESIGN

This was a retrospective study.

SETTING

The study was conducted in a tertiary referral unit for interventional endoscopy in the United Kingdom.

PATIENTS

A total of 116 colorectal lesions were resected using endoscopic submucosal dissection or hybrid endoscopic submucosal dissection in 107 patients.

MAIN OUTCOME MEASURES

Outcomes included complications, recurrence, requirement for surgery, en bloc and R0 resection.

RESULTS

One hundred sixteen lesions (mean size 58.8mm) were resected using endoscopic submucosal dissection (n = 58) and hybrid endoscopic submucosal dissection (n = 58). Eighty-two (70.7%) had failed attempts at resection (n = 58) or extensive sampling before referral. Twelve contained invasive adenocarcinoma; endoscopic resection was curative in 6. Only 2 of 6 patients with noncurative endoscopic resection agreed to surgery, and none had lymph node metastases. Six of 7 perforations were successfully treated with endoscopic clips. Where endoscopic submucosal dissection was used alone, en bloc resection was achieved in 93% and R0 resection was achieved in 91%. Two patients experienced recurrence; both were managed with endoscopic resection.

LIMITATIONS

This was a retrospective study. Procedures were planned as endoscopic submucosal dissection, but some may have been converted to hybrid endoscopic submucosal dissection and not recorded.

CONCLUSION

Colorectal endoscopic submucosal dissection can be used in a Western center as part of a standard lesion-specific approach to deliver effective organ-conserving treatment to patients with large challenging lesions. Lesion assessment in Western practice should be improved to reduce the incidence of prior heavy manipulation and to guide appropriate referral. See Video Abstract at http://links.lww.com/DCR/A601.

Combining eastern and western practices for safe and effective endoscopic resection of large complex colorectal lesions

BACKGROUND

Endoscopic resection of large colorectal polyps is well established. However, significant differences in technique exist between eastern and western interventional endoscopists. We report the results of endoscopic resection of large complex colorectal lesions from a specialist unit that combines eastern and western techniques for assessment and resection.

PATIENTS AND METHODS

Endoscopic resections of colorectal lesions of at least 2 cm were included. Lesions were assessed using magnification chromoendoscopy supplemented by colonoscopic ultrasound in selected cases. A lesion-specific approach to resection with endoscopic mucosal resection or endoscopic submucosal dissection (ESD) was used. Surveillance endoscopy was performed at 3 (SC1) and 12 (SC2) months.

RESULTS

Four hundred and sixty-six large (≥20 mm) colorectal lesions (mean size 54.8 mm) were resected. Three hundread and fifty-six were resected using endoscopic mucosal resection and 110 by ESD or hybrid ESD. Fifty-one percent of lesions had been subjected to previous failed attempts at resection or heavy manipulation (≥6 biopsies). Nevertheless, endoscopic resection was deemed successful after an initial attempt in 98%. Recurrence occurred in 15% and could be treated with endoscopic resection in most. Only two patients required surgery for perforation. Nine patients had postprocedure bleeding; only two required endoscopic clips. Ninety-six percent of patients without invasive cancer were free from recurrence and had avoided surgery at last follow-up.

CONCLUSION

Combining eastern and western practices for assessment and resection results in safe and effective organ-conserving treatment of complex colorectal lesions. Accurate assessment before and after resection using magnification chromoendoscopy and a lesion-specific approach to resection, incorporating ESD where appropriate, are important factors in achieving these results.

Management of complex polyps of the colon and rectum

PUPRPOSE

Benign polyps that are technically challenging and unsafe to remove via polypectomy are known as complex polyps. Concerns regarding safety and completeness of resection dictate they undergo advanced endoscopic techniques, such as endoscopic mucosal resection or surgery. We provide a comprehensive overview of complex polyps and current treatment options.

METHODS

A review of the English literature was conducted to identifyarticles describing the management of complex polyps of the colon and rectum.

RESULTS

Endoscopic mucosal resection is the standard of care for the majority of complex polyps. Only polyps that fail endoscopic mucosal resection or are highly suspicious of invasive cancer but which cannot be removed endoscopically warrant surgery.

CONCLUSION

Several factors influence the treatment of a complex polyp; therefore, there cannot be a "one-size-fitsall" approach. Treatment should be tailored to the lesion's characteristics, the risk of adverse events, and the resources available to the treating physician.

Transanal minimally invasive surgery for rectal polyps and selected malignant tumors: caution concerning intermediate-term functional results

PURPOSE

Transanal minimally invasive surgery (TAMIS) is gaining worldwide popularity as an alternative for the transanal endoscopic microsurgery (TEMS) method for the local excision of rectal polyps and selected neoplasms. Data on patient reported outcomes regarding short-term follow-up are scarce; data on functional outcomes for long-term follow-up is non-existent.

METHODS

We used the fecal incontinence severity index (FISI) to prospectively assess the fecal continence on the intermediate-term follow-up after TAMIS. The primary outcome measure is postoperative fecal continence. Secondary outcome measures are as follows: perioperative and intermediate-term morbidity.

RESULTS

Forty-two patients (m = 21:f = 21), median age 68.5 (range 34-94) years, were included in the analysis. In four patients (9.5%), postoperative complications occurred. The median follow-up was 36 months (range 24-48). Preoperative mean FISI score was 8.3 points. One year after TAMIS, mean FISI score was 5.4 points (p = 0.501). After 3 years of follow-up, mean FISI score was 10.1 points (p = 0.01). Fecal continence improved in 11 patients (26%). Continence decreased in 20 patients (47.6%) (mean FISI score 15.2 points, [range 3-31]).

CONCLUSIONS

This study found that the incidence of impaired fecal continence after TAMIS is substantial; however, the clinical significance of this deterioration seems minor. The present data is helpful in acquiring informed consent and emphasizes the need of proper patient information. Functional results seem to be comparable to results after TEMS. Furthermore, we confirmed TAMIS is safe and associated with low morbidity.

Colorectal endoscopic submucosal dissection: patient selection and special considerations

Endoscopic submucosal dissection (ESD) enables en bloc resection of large complex colorectal superficial neoplastic lesions, resulting in very low rates of local recurrence, high-quality pathologic specimens for accurate histopathologic diagnosis and potentially curative treatment of early adenocarcinoma without resorting to major surgical resection. The safety and efficacy of the technique, which was pioneered in the upper gastrointestinal tract, has been established by the consistently impressive outcomes from expert centers in Japan and some other eastern countries. However, ESD is challenging to perform in the colorectum and there is a significant risk of complications, particularly in the early stages of the learning curve. Early studies from western centers raised concerns about the high complication rates, and the impressive results from Japanese centers were not replicated. As a result, many western endoscopists are skeptical about the role of ESD and few centers have incorporated the technique into their practice. Nevertheless, although the distribution of expertise, referral centers and modes of practice may differ in Japan and western countries, ESD has an important role and can be safely and effectively incorporated into western practice. Key to achieving this is meticulous lesion assessment and selection, appropriate referral to centers with the necessary expertise and experience and application of the appropriate technique individualized to the patient. This review discusses the advantages, risks and benefits of ESD to treat colorectal lesions and the importance of preprocedure lesion assessment and in vivo diagnosis and outlines a pragmatic rationale for appropriate lesion selection as well as the patient, technical and institutional factors that should be considered.