Two large Paris 0-IIa + IIc colonic lesions were found in the same person. High-definition white-light (a) and NBI (b) images are shown of the lesion in the cecum. White-light images of the second large polyp (c) with a mucous cap that remained despite irrigation were found in the ascending colon. Both polyps were removed by underwater EMR and found to be serrated sessile polyps without dysplasia
The acquisition of other skills in lesion assessment has been evaluated, though these are frequently more complicated. Togashi et al. [36] have described the learning curve and accuracy of optical diagnosis of neoplastic and nonneoplastic polyps using the Kudo pit pattern [37] . In this study, sequential observation of lesions under chromo- and magnification endoscopy demonstrated an improvement to over 90% sensitivity for correctly identifying neoplastic lesions after at least 200 sequential assessments. While this does suggest a threshold for competence, assuming the benchmark of 90% is appropriate, implementation outside of Japan may be challenging. Many endoscopic platforms which are routinely available in the West do not offer a true optical magnification capability . Use of chromoendoscopy for optical diagnosis of the mucosal pit pattern using a high-definition endoscope that lacks optical magnification may introduce issues with fine-detail image resolution and therefore might not be sufficient to perform this task consistently [38].
A 1.5-cm sessile polyp (Paris 0-Is) was found in the splenic flexure and high-definition white-light images (a) do not show the surface pattern well. NBI (b) better demonstrated the meshed capillary pattern , which in this case showed disordered vessels with some areas of avascularity. While there was concern for early invasive cancer (Sano type IIIB), given the relatively small size and lack of other surface features that might suggest deeper invasion (tenting, bridging folds, etc.), en bloc underwater EMR was performed (c) with complete resection and no bleeding or perforation (d). Pathology showed a well-differentiated adenocarcinoma with invasion into the superficial submucosa but negative margins (>1-mm negative deep margin). In this case, the risk of lymph node metastasis is likely around 5%, and the patient was directed to meet a colorectal surgeon to discuss the risks and benefits of further laparoscopic surgical resection, with the alternative being close endoscopic surveillance and yearly CT scans
Mucosal Resection Technique
Following lesion identification and characterization, the endoscopist then prepares to tackle the fundamental act of removing the superficial neoplastic lesion. As the practice of mucosal resection has matured, understanding of the technical aspects of both EMR and ESD has become increasingly developed [41, 42]. For each technique that could be employed, there are fundamental steps associated with performance of an optimal resection. These may vary based upon lesion location, characteristics, technique, or equipment utilized. An extensive discussion of how to perform these procedures is beyond the scope of this chapter and is discussed elsewhere in the textbook.
In the case of traditional mucosal resection, simply the process of creating a submucosal lift has numerous technical considerations: choosing the proper submucosal injectate solution , injecting the lesion appropriately to facilitate a lift without obscuring visualization, assessing for an adequate or inadequate lift, and interpreting if the presence of poor lifting represents tumor invasion or benign submucosal fibrosis [43]. Snare resection is no less complex with regard to optimal technique and has several facets: lesion and scope orientation to facilitate technical success, incorporating a normal mucosal border within the snare (i.e., a 2–3-mm rim of normal tissue), maintaining a submucosal plane in piecemeal resection using the snare edge , and the application of cautery by using a modern electrosurgical generator. Each and any of these technical steps could be observed and evaluated as a measure of competence, were there a consistent methodology available to do so. Additionally, there are a number of other higher-level decisions made by endoscopists during EMR: attempting en bloc resection whenever possible, removing large or dysplastic appearing nodules in a single piece (given an increased risk of focal malignancy), and minimizing the number of overall fragments when en bloc resection is not possible [43, 44].
Learning Curves and Direct Observation of Polypectomy Skills (DOPyS)
Although no societal recommendation for a threshold number of EMR cases in training has been established, there does exist limited data regarding skill acquisition and the learning curves for EMR among practicing academic interventional endoscopists. In a retrospective series by Bhurwal et al. [34], a total of 578 consecutive colonic EMR procedures, performed by 3 endoscopists over a 9-year period, were tabulated and analyzed. Three relatively narrow outcomes were included: residual neoplasia upon interval surveillance, immediate assessment that an EMR was incomplete, and the occurrence of immediate bleeding as an adverse event. For each of three physicians, the occurrence of residual neoplasia (grossly and by surveillance biopsies) fell below 20% and plateaued by procedure number 100. Immediate bleeding was generally rare throughout the study and was acceptably below 5% by case 100 for all of the endoscopists. Although there were several limitations inherent in this series that may have prolonged the learning curve (referral bias to a tertiary care center, self-teaching environment, retrospective series, etc.), the observed number of cases required to establish a plateau of residual neoplasia was higher than expected. To date, this study represents the only published learning curve data with respect to EMR of large laterally spreading lesions in the colon.
Published data evaluating the rate of acquiring skills necessary to perform ESD in Japan exist and are more robust. In 2005, Gotoda et al. [45] reported that early proficiency in gastric ESD could be seen after 30 cases during intensive training. In 2012, Yamamoto et al. [28] provided observational evidence that by 40 gastric ESDs, trainees may have sufficient skill to reliably remove superficial mucosal lesions, without ulceration, that were less than 2 cm in size. With continued instruction and experience through 80 cases, trainees routinely demonstrated outcomes that approximated their expert instructors. In 2010, Hotta et al. [46] described the first learning curve for colonic ESD in a single endoscopist from Saku Central Hospital in Japan. They demonstrated that 40 ESD procedures were required to avoid an unacceptable rate of perforation (rate dropped from 12.5% to 5%) and that a total of 80 procedures were required to establish an acceptable rate of en bloc, R0 resection (rate increased from 85% to 92.5%). Translation of gastric ESD experience to colonic lesions appears more straightforward. In 2011, Sakamoto et al. [47] reported that trainees with experience in gastric ESD could successfully perform supervised colorectal ESD safely after approximately 30 procedures.
The Western experience with ESD skill acquisition has been more challenging, as the methods used thus far to disseminate ESD skill in Europe and the United States have been fractured and inconsistent. While reports of learning curves for Western endoscopists exist [29, 48, 49], these experiences draw upon training that has been universally disparate. Each published experience is similar only in that the individual pathways to competence have been distinctly different than others. As such, these data likely have only limited translational value to typical Western graduate (fellowship level) or postgraduate endoscopy training concerning ESD.
While learning curves may provide insight into the degree of experience necessary to attain competency in mucosal resection, they may not be reliable measures at the level of an individual trainee. This problem, and how it pertains to routine colonoscopy with polypectomy, has been widely recognized [21]. Out of concerns for inadequate training in routine polypectomy, an expert working group within the United Kingdom deconstructed the process of polypectomy into a 33-item checklist entitled the Direct Observation of Polypectomy Skills (DOPyS) tool [50, 51]. Skills were divided into several sections including (1) optimizing the view of/access to the polyp, (2) stalked polyps, (3) small sessile lesions, and (4) post-polypectomy. Endoscopic nontechnical skills were also included at the end of the assessment form. For each item on the checklist, a 4-point score is given which was intended to evaluate the subject by maneuver: 1 (standards not met), 2 (some uncorrected errors), 3 (competent and safe), and 4 (highly skilled). This methodology was developed, validated, and shown to be reliable in two sequential publications by Gupta et al. [50, 51] These studies demonstrated that assessors who had been formally trained in DOPyS could successfully and consistently delineate between procedures performed by expert endoscopists and those performed by trainees, so long as the assessor was able to observe at least five separate polypectomies performed by each individual.
Despite its promising value, the DOPyS has not been validated for use in more advanced mucosal resection. Polypectomies performed during the DOPyS validation studies were uniformly less than 18 mm in size, which is smaller than lesions typically considered for EMR or ESD (usually >20 mm in size). Further, the tool as written is not applicable to techniques apart from conventional injection-lift EMR . Nonetheless, a similar instrument could be of great value in establishing uniform competency-based mucosal resection training. If validated appropriately, such a method could be applied throughout a graduate or postgraduate training program, and used at intervals guided by data extracted from published learning curves, in order to establish an individual trainee’s progression to competence.
The Importance of Feedback
Well-developed CBE is based upon the principle of self-regulated learning. Perhaps the most critical aspect of this process is the capacity of an individual to assess the results of learning (e.g., trainee’s performance) and make adjustments, prospectively [52]. Feedback is central to this process of assessment and adaptability, as it allows the trainee to identify areas of weakness that are in need of additional attention. Feedback may be internal (self-assessment) or external, with the latter frequently delivered by one’s instructor, mentor, or program-director. Internal feedback is important, but sometimes can be unreliable, and is, in any case, outside the control of an institutional training program. External feedback is more likely to be accurate [53] and, when delivered by a subject matter expert, can include guidance for incremental improvement.
Despite its extremely high value, external feedback typically suffers from poor delivery and inadequate, poorly-timed, or generalized content. Fundamentally, external feedback is difficult because it takes place as an exchange within interpersonal relationships of varying resiliency. A strong relationship, with trust and credibility by both partners, allows for valuable insight and communication. A weak relationship may be harmed by the delivery of criticism or corrective feedback, making this either less effective or less likely to be delivered in the first place. While not explicitly stated, one of the major conceptual advantages of a traditional apprenticeship is this relationship. In the classical sense, a mentor and apprentice are expected to have both a close and invested working relationship built on trust and common interest. Such a relationship should allow for the provision of regular and honest formative feedback, which may even be bilateral (How can you/I learn better? How can you/I teach better?).
One potential drawback to an educational model with explicitly defined competencies and learner-directed focus is this need to provide frequent and accurate feedback. Evaluating procedural skills seems particularly susceptible to failures, especially at the outset of mucosal resection training, when trainees are expected to be at the first stage of learning (unconsciously incompetent). During this time they may possess only limited insight in order to make self-assessments, and the relationship with a mentor may be nascent or underdeveloped. Great care should be taken at all times to ensure that feedback is given effectively, frequently, and within a nonjudgmental and constructive environment.
Training Considerations for “Nontraditional Students ” and Continuing Medical Education (CME)
Much of what has been discussed previously is based upon the assumption that training in mucosal resection occurs in the milieu of a traditional graduate GI fellowship or postgraduate educational program in advanced endoscopy (formal advanced endoscopy fellowship training). While this may be the standard setting in which such skills are developed for new learners, most practicing endoscopists who perform EMR did not develop this technique under such formal circumstances. Regardless of how experience in mucosal resection is acquired, societal and professional expectations would suggest that the practicing endoscopist should demonstrate competency that is on par with graduates of established training programs (and vice versa). This remains inherently problematic, as there are no societally endorsed criteria for judging competency , no validated observational assessment tools, and limited data on learning curves even to suggest a minimum threshold volume of procedures necessary to use as a surrogate for competence.
The previous example of Western experts who perform ESD is perhaps the most striking conglomeration of skill acquisition by nontraditional means [29, 49, 54] and may be beneficial in devising a methodology for practicing endoscopists to acquire EMR skills at the CME level (during active clinical practice and after completion of all endoscopic training). Draganov et al.29 specifically highlight the impact that observation of live cases can have on acquiring new skills for an already experienced endoscopist. In his published experience, Dr. Draganov’s ESD learning curve was divided into three phases: (1) pre-observation , during which ESD was performed on animal models prior to observation; (2) observation , during which Dr. Draganov visited Japan and observed live ESD cases at experienced centers over a 5-week period; and (3) post-observation , where additional ex vivo animal models were again used to garner additional experience. Following the observation period, resections were completed on models with significant gains in efficiency (shorter time) and observable trends toward reduced incomplete resection rates and adverse events. This was notable, especially considering that ESD requires significant technical expertise distinctly disparate from traditional polypectomy, while traditional EMR is more akin to an extension or refinement of traditional polypectomy skills [23, 27].
Observation can be accomplished by practicing endoscopists under a number of different circumstances. There are various national and international endoscopy conferences at which practicing endoscopists may attend didactic lectures, breakout sessions, and live demonstrations which showcase EMR or ESD techniques [55, 56]. In keeping with the prior example, these courses may provide a valuable adjunctive experience to solidify skills among practicing physicians who already have extensive polypectomy experience and wish to gain skill in EMR or become exposed to ESD. These courses have several limitations , as many provide short-duration hands-on training limited to a few hours and utilize ex vivo animal models that cannot simulate intraprocedural hemorrhage or clinical instability in the setting of perforation. While these courses offer an important and convenient method for endoscopists to be taught by experts, they may be best digested by the endoscopic journeyman rather than the apprentice.
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