Wide Field Endoscopic Resection for Advanced Colonic Mucosal Neoplasia: Current Status and Future Directions
2012; Elsevier BV; Volume: 10; Issue: 9 Linguagem: Inglês
10.1016/j.cgh.2012.05.020
ISSN1542-7714
AutoresBronte A. Holt, Michael J. Bourke,
Tópico(s)Gastrointestinal Tumor Research and Treatment
ResumoMost colonic adenomas are ≤10 mm and are routinely treated by colonoscopic polypectomy with long-term health benefits. Nonpolypoid lesions ≥20 mm, whether sessile or flat and laterally spreading, are forms of advanced mucosal neoplasia that cannot be managed by conventional polypectomy and are often referred for surgery. However, the majority of these lesions when carefully assessed are found to be noninvasive and can be safely and effectively treated by advanced endoscopic techniques including endoscopic mucosal resection or endoscopic submucosal dissection with resultant cost, morbidity, and mortality benefits. Lesion assessment is a critical component. Enhanced imaging methods provide the opportunity for accurate pathological characterization, informing treatment decisions, without the need for previous histologic confirmation. Techniques of advanced endoscopic resection are still in evolution and further improvements, including hybrid techniques, bringing less technically challenging and shorter procedures with superior safety can be reasonably expected in the next decade. Safety is a fundamental consideration. Methods of early recognition of complications, risk stratification, and management pathways are being developed and refined. Standardization, validation, and adoption of these technological developments will improve endoscopic interpretation and therapy and in combination with an increased understanding of adenoma molecular biology, will result in a progressively more individualized lesion-specific endoscopic approach. The future of advanced endoscopic resection in the colon is promising, and the next few years should see the boundaries of endoscopic resection expand well beyond the limits of what we know today. Most colonic adenomas are ≤10 mm and are routinely treated by colonoscopic polypectomy with long-term health benefits. Nonpolypoid lesions ≥20 mm, whether sessile or flat and laterally spreading, are forms of advanced mucosal neoplasia that cannot be managed by conventional polypectomy and are often referred for surgery. However, the majority of these lesions when carefully assessed are found to be noninvasive and can be safely and effectively treated by advanced endoscopic techniques including endoscopic mucosal resection or endoscopic submucosal dissection with resultant cost, morbidity, and mortality benefits. Lesion assessment is a critical component. Enhanced imaging methods provide the opportunity for accurate pathological characterization, informing treatment decisions, without the need for previous histologic confirmation. Techniques of advanced endoscopic resection are still in evolution and further improvements, including hybrid techniques, bringing less technically challenging and shorter procedures with superior safety can be reasonably expected in the next decade. Safety is a fundamental consideration. Methods of early recognition of complications, risk stratification, and management pathways are being developed and refined. Standardization, validation, and adoption of these technological developments will improve endoscopic interpretation and therapy and in combination with an increased understanding of adenoma molecular biology, will result in a progressively more individualized lesion-specific endoscopic approach. The future of advanced endoscopic resection in the colon is promising, and the next few years should see the boundaries of endoscopic resection expand well beyond the limits of what we know today. Colonoscopic polypectomy is a fundamental tool in colorectal cancer prevention, reducing the anticipated incidence and mortality of colorectal malignancy by approximately 80% and 50%, respectively, in long-term follow up.1Winawer S.J. Zauber A.G. Ho M.N. et al.Prevention of colorectal cancer by colonoscopic polypectomy The National Polyp Study Workgroup.N Engl J Med. 1993; 329: 1977-1981Crossref PubMed Scopus (3862) Google Scholar, 2Zauber A.G. Winawer S.J. O'Brien M.J. et al.Colonoscopic polypectomy and long-term prevention of colorectal-cancer deaths.N Engl J Med. 2012; 366: 687-696Crossref PubMed Scopus (1968) Google Scholar More than 90% of adenomatous lesions are 10 mm are termed laterally spreading tumors. They grow laterally along the surface of the bowel and may reach an enormous size before exhibiting invasive behavior. Sessile lesions have a greater frequency of high-grade dysplasia and early invasive disease compared with polypoid lesions of equivalent size.4Soetikno R.M. Kaltenbach T. Rouse R.V. et al.Prevalence of nonpolypoid (flat and depressed) colorectal neoplasms in asymptomatic and symptomatic adults.JAMA. 2008; 299: 1027-1035Crossref PubMed Scopus (505) Google Scholar Currently there is no umbrella term for the different types of large sessile colorectal lesions, and this review will use the term advanced mucosal neoplasia (AMN) to describe large sessile lesions of Paris 0–II (flat) and 0–Is (elevated) morphology ≥20 mm and combinations of these.5Bourke M. Endoscopic mucosal resection in the colon: a practical guide.Tech Gastrointest Endosc. 2011; 13: 35-49Abstract Full Text Full Text PDF Scopus (49) Google ScholarTherapeutic options for colonic AMN include endoscopic mucosal resection (EMR), endoscopic submucosal dissection (ESD), and surgery. The colonic EMR technique has evolved substantially since it was first described by Deyhle et al in 19736Deyhle P. Largiader F. Jenny S. et al.A method for endoscopic electroresection of sessile colonic polyps.Endoscopy. 1973; 5: 38-40Crossref Scopus (190) Google Scholar and is now widely practiced. Prospective multicenter data confirm that wide field EMR is safe and effective therapy even for very large or complex lesions and avoids the need for surgery in most patients.7Moss A. Bourke M.J. Williams S.J. et al.Endoscopic mucosal resection outcomes and prediction of submucosal cancer from advanced colonic mucosal neoplasia.Gastroenterology. 2011; 140: 1909-1918Abstract Full Text Full Text PDF PubMed Scopus (426) Google Scholar Moreover, prospective data show that EMR for AMN results in major net health savings of more than US$10,000 and 6 bed-days per patient when compared with an ideal surgical outcome without complications.8Swan M.P. Bourke M.J. Alexander S. et al.Large refractory colonic polyps: is it time to change our practice? A prospective study of the clinical and economic impact of a tertiary referral colonic mucosal resection and polypectomy service.Gastrointest Endosc. 2009; 70 (with videos): 1128-1136Abstract Full Text Full Text PDF PubMed Scopus (155) Google Scholar Modeling with validated preoperative scoring systems suggests that endoscopic treatment results in a substantial mortality benefit in this often elderly, comorbid patient cohort.9Risk prediction in surgery Colorectal-POSSUM scoring.http://www.riskprediction.org.uk/index-cr.phpGoogle Scholar, 10Ahlenstiel G. Bourke M.J. Moss A. et al.Actual endoscopic vs predicted surgical mortality for the treatment of large (>20mm) laterally spreading tumours (LSTs) and sessile lesions of the colon: Outcomes from a large prospective multicenter trial.Gastroenterology. 2010; 138: S635-S636Google ScholarThe future of endoscopic resection for AMN is exciting. Recent technological advances are improving lesion assessment and standardization, and new methods and techniques are being developed to enhance procedural safety and efficacy.Lesion AssessmentOverview AssessmentCareful systematic endoscopic assessment is essential. This commences with a global evaluation of the lesion, followed by focused interrogation of any areas of concern. Identification of lesions with possible submucosal invasion (SMI) informs the choice of therapeutic strategy. This may dictate a change in endoscopic technique or referral for consideration of surgical treatment. En bloc resection is preferred if there is a substantial risk of SMI. The assessment also identifies features that may hinder complete endoscopic clearance such as fixity, scarring, and inaccessibility.Lesion morphology is best described using the Paris system of endoscopic classification of superficial neoplastic lesions11Endoscopic Classification Review GroupUpdate on the Paris classification of superficial neoplastic lesions in the digestive tract.Endoscopy. 2005; 37: 570-578Crossref PubMed Scopus (584) Google Scholar (Figure 1, Figure 2). A 2.5-mm height limit is used to broadly divide sessile (0–Is) from flat (0–II) lesions. This threshold of 2.5 mm, which corresponds to the height of a closed biopsy forcep, is in practice found to be a bit arbitrary as many undulating homogeneous and typical 0-IIa lesions may be elevated up to 3–3.5 mm above the mucosa. Sessile lesions are further divided into granular (G, nodular), nongranular (NG, smooth), or mixed morphologies based on their surface appearance. Paris classification and surface morphology stratifies for the risk of SMI. Approximately 70% of sessile lesions ≥20 mm are 0–IIa or 0–IIa + Is, with more than 90% of these being G type. A homogeneous 0–IIa G lesion has approximately 1% risk of SMI. In contrast, 0–IIa + c NG lesions have the greatest risk of SMI at approximately 67% (relative risk, 54; P < .001). The risk of SMI in 0–IIa NG lesions without a depressed component is intermediate at 15%–20%.7Moss A. Bourke M.J. Williams S.J. et al.Endoscopic mucosal resection outcomes and prediction of submucosal cancer from advanced colonic mucosal neoplasia.Gastroenterology. 2011; 140: 1909-1918Abstract Full Text Full Text PDF PubMed Scopus (426) Google Scholar The risk of focal SMI is increased in depressed lesions (Paris 0–IIc) and lesions with focal depression (Paris 0–IIa + c or Paris 0–Is + c) particularly if the morphology is NG.12Hurlstone D.P. Sanders D.S. Cross S.S. et al.Colonoscopic resection of lateral spreading tumours: a prospective analysis of endoscopic mucosal resection.Gut. 2004; 53: 1334-1339Crossref PubMed Scopus (236) Google Scholar, 13Oka S. Tanaka S. Kanao H. et al.Therapeutic strategy for colorectal laterally spreading tumour.Dig Endsoc. 2009; 21: S43-S46Crossref Scopus (67) Google Scholar, 14Uraoka T. Saito Y. Matsuda T. et al.Endoscopic indications for endoscopic mucosal resection of laterally spreading tumours in the colorectum.Gut. 2006; 55: 1592-1597Crossref PubMed Scopus (339) Google Scholar Among 0–IIa + Is lesions, the risk of SMI is 10% and is most frequently beneath the Is component. Therefore, we advocate resection of the Is component first if piecemeal excision is planned, and this specimen should be retrieved separately for histopathologic analysis if possible. These simple global assessment tools, available to all endoscopists, permit a basic estimation of SMI risk in all colonic AMN.Figure 2Examples of AMN treated by EMR. (A) A 40-mm Paris 0–IIa + Is G lesion located on the posteromedial wall of the ascending colon. (B) EMR was performed in both anterograde position and retroflexion. (C) The EMR defect is clean with characteristic blue "mat" SM staining and a number of visible vessels. (D) A near circumferential 100-mm homogenous Paris 0–IIa G lesion in the transverse colon. Histology showed tubulovillous adenoma with low-grade dysplasia. (E) The injection expands the SM layer and facilitates a large and safe resection. (F) The final vast defect with numerous visible and herniated vessels. The transverse colon is at low risk for post-EMR bleeding, and despite the resection size and number of vessels, no postprocedural bleeding occurred.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Focal AssessmentDisruption to a homogenous pit pattern (PP) or mucosal topography (eg, nodule or depression) alerts the endoscopist to examine this area carefully (Figure 3). The mucosal PP is examined with high definition white light and is classified according to the Kudo system.15Kudo S. Hirota S. Nakajima T. et al.Colorectal tumours and pit pattern.J Clin Pathol. 1994; 47: 880-885Crossref PubMed Scopus (606) Google Scholar Among AMN, PP type IV is most common, is usually seen with large G lesions, and implies tubulovillous histology. PP type III is seen with NG lesions, in which case the lesion is usually a tubular adenoma. Kudo PP VI (irregularly arranged pits with type IIIs, IIIL, and IV PPs) or VN (nonstructural PPs) indicates a high risk of at least intramucosal or invasive malignancy, respectively.7Moss A. Bourke M.J. Williams S.J. et al.Endoscopic mucosal resection outcomes and prediction of submucosal cancer from advanced colonic mucosal neoplasia.Gastroenterology. 2011; 140: 1909-1918Abstract Full Text Full Text PDF PubMed Scopus (426) Google Scholar, 15Kudo S. Hirota S. Nakajima T. et al.Colorectal tumours and pit pattern.J Clin Pathol. 1994; 47: 880-885Crossref PubMed Scopus (606) Google Scholar Previously PP determination required potentially cumbersome chromoendoscopy, but contemporary endoscopes provide high definition white light imaging with sufficient accuracy in most situations and additional convenient "push-button" technologies that allow efficient virtual chromoendoscopy.16Subramaniam V. Mannath J. Ragunath K. et al.Utility of Kudo pit pattern for distinguishing adenomatous from non adenomatous colonic lesions in vivo: meta-analysis of different endoscopic techniques.Gastrointest Endosc. 2009; 69: AB277Abstract Full Text Full Text PDF Google Scholar Narrow band imaging (NBI) uses light filters to narrow the bandwidth of the endoscope's projected light to 30 nm wide spectra of blue (415 nm) and green (540 nm). The "returned" light selectively carries information from the area of most interest, the mucosal layer.17Gono K. Yamazaki K. Doguchi N. et al.Endoscopic observation of tissue by narrowband illumination.Opt Rev. 2003; 10: 211-215Crossref Scopus (268) Google Scholar, 18Ng S.C. Lau J.Y. Narrow-band imaging in the colon: limitations and potentials.J Gastroenterol Hepatol. 2011; 26: 1589-1596Crossref PubMed Scopus (19) Google Scholar Postprocessing imaging techniques, such as Fujinon intelligent chromoendoscopy and I-scan, use computer algorithms to modulate the postprocessor image, highlighting surface morphology, vessels, and PPs. The modified Sano system classifies lesions on the basis of their mucosal microvasculature as seen with NBI. In a benign adenoma, there is a typical meshed brown capillary network corresponding to capillaries surrounding mucosal glands (pits) (Sano II). This is corrupted in the presence of cancer with irregular capillaries with complex branching, blind endings, or avascular areas (Sano type IIIa and IIIb).19Katagiri A. Fu K.I. Sano Y. et al.Narrow band imaging with magnifying colonoscopy as diagnostic tool for predicting histology of early colorectal neoplasia.Aliment Pharmacol Ther. 2008; 27: 1269-1274Crossref PubMed Scopus (121) Google Scholar No single high-risk feature is 100% specific for invasive disease; however, the risk of SMI increases when more than 1 high-risk feature is present.7Moss A. Bourke M.J. Williams S.J. et al.Endoscopic mucosal resection outcomes and prediction of submucosal cancer from advanced colonic mucosal neoplasia.Gastroenterology. 2011; 140: 1909-1918Abstract Full Text Full Text PDF PubMed Scopus (426) Google ScholarFigure 3After gross assessment of lesion morphology, areas of concern are focally interrogated with high-definition white light endoscopy and NBI. (A and B) 25-mm Paris 0–IIa + c NG rectal lesion with Kudo PP Vn and Sano capillary pattern IIIb. This was resected en bloc, and there was deep SMI on histology with a clear deep margin. The patient elected for careful endoscopic and radiologic surveillance. (C and D) 20-mm Paris 0–IIa + c NG lesion at the splenic flexure with Kudo PP Vi and Sano capillary pattern IIIa/b. The patient had surgical resection, and histology showed a submucosally invasive cancer arising from a tubular adenoma (T1N0M0). (E and F) 30-mm Paris 0–Is + c NG lesion in the distal sigmoid colon with a clear transition seen from Kudo PP IV to Vi. En bloc excision was performed, and histology showed a tubular adenoma with intramucosal cancer.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Preparation for EMRElectrosurgery UnitSophisticated generators allow a range of different outputs to be chosen depending on the clinical situation. Microprocessor-controlled electrosurgical generators delivering alternating cycles of high-frequency short-pulse cutting with more prolonged coagulation current offer clear advantages (VIO 300D; ERBE, Tübingen, Germany. ESG100; Olympus Medical, Toyko, Japan). Tissue impedance is sensed via signals from the return electrode, allowing appropriate adjustment of power output to limit unintentional adjacent or deep tissue injury.Submucosal Injection SolutionThe submucosal (SM) injection creates a fluid "cushion" between the mucosa and muscularis propria (MP), reducing the risk of inadvertent deep resection, transmural thermal injury, and perforation. The ideal SM injectate should be inexpensive, easy to prepare and inject, and provide a sustained, well-circumscribed mucosal elevation to facilitate tissue capture. Normal saline is most commonly used but is limited by a nonsustained, diffuse mucosal lift. Level 1 evidence shows superior technical outcomes with the use of a colloidal solution in comparison with saline, including significantly fewer injections, fewer resections, and a halving of total EMR time.20Moss A. Bourke M.J. Kwan V. et al.Succinylated gelatin substantially increases en bloc resection size in colonic EMR: a randomized, blinded trial in a porcine model.Gastrointest Endosc. 2010; 71: 589-595Abstract Full Text Full Text PDF PubMed Scopus (45) Google Scholar, 21Moss A. Bourke M.J. Metz A. A randomized, double-blind trial of succinylated gelatin sub mucosal injection for endoscopic resection of large sessile polyps of the colon.Am J Gastroenterol. 2010; 105: 2375-2382Crossref PubMed Scopus (112) Google Scholar Succinylated gelatin (Gelofusine; Braun, Melsungen, Germany) is used as standard in our unit; however, it is not universally available or accepted as it is derived from bovine protein. A number of other fluids have been trialed as the SM injectate.22Kantsevoy S.V. Adler D.G. et al.ASGEEndoscopic mucosal resection and endoscopic submucosal dissection.Gastrointest Endosc. 2008; 68: 11-18Abstract Full Text Full Text PDF PubMed Scopus (263) Google Scholar Inexpensive plasma volume expanders are a logical choice due to their wide availability and safety. In the United States, compounds such as hydroxyethyl starch (Voluven; Pharmatel Fresenius Kabi, Bad Homburg, Germany), a synthetic colloid commonly used for hypotension could be used.23Holt B.A. Bassan M.S. Bourke M.J. et al.The search for the optimal submucosal injection fluid: colonic endoscopic resection with hydroxyethyl starch, a porcine study.Gastrointest Endosc. 2012; 75 ([abstract]): AB421Abstract Full Text Full Text PDF Google ScholarA biologically inert blue dye (80 mg indigo carmine blue per 500 mL solution) is used. It is avid for the loose areolar connective tissue of the SM layer. The resultant homogenous blue expanse confirms the resection is taking place in the correct plane. Nonstained tissue within the defect is readily identified as residual adenoma (mucosa) or deep resection (MP or deeper). In addition, the dye delineates the perimeter of the lesion, which is important for barely perceptible lesions (eg, 0–IIb serrated lesions [SLs]), and demarcates the extent of the SM cushion and thus the safe resection margin. Nonstained areas within the EMR defect can be confirmed as submucosa by irrigation with the injection fluid, as the dye is rapidly taken up by the SM connective tissue. This provides reassurance or prompts consideration of intervention. We prefer adrenaline (1:100,000) in the injectate to maintain a bloodless resection field. The effect on post procedural bleeding is unknown.Snare SelectionEvaluation of the lesion size, morphology, and location allows selection of the most appropriate snare (Figure 4). Stiff serrated (spiral) snares are preferred to increase tissue capture. The 20-mm spiral snare (wire diameter, 0.48 mm) is the "work horse" for large en bloc or wide field piecemeal EMR. In addition, a complete range of sizes (10–20 mm and occasionally larger) and configurations (oval, round, and hexagonal) are required. Small thin wire snares (wire diameter, 0.3 mm) are used to remove tissue where greater precision is required such as at tight angulations, high-risk locations and situations (periappendiceal, SM fibrosis) and small residual tissue within and at the margin of the defect.Figure 4A variety of snares are used for EMR. From left to right: serrated snare and standard oval snares, and thin wire minihex, mini-oval, and micro mini snares.View Large Image Figure ViewerDownload Hi-res image Download (PPT)EMR TechniquePositioningLesion access and endoscopic orientation should be optimized. Difficulties such as poor luminal insufflation, liquid pooling, or suboptimal orientation to the lesion will often be swiftly resolved by a change in patient position. Orienting the lesion to maximize the influence of gravity may prove surprisingly useful for poorly accessible lesions, particularly in the rectosigmoid and right colons. Retroflexion may be necessary to completely assess or resect the lesion, in which case a thinner caliber endoscope may be required (pediatric colonoscope or gastroscope).Injection TechniqueA strategically placed injection elevates the lesion into the lumen and toward the colonoscope, improving access for EMR. The needle tip is tangentially positioned against the mucosal surface, and the assistant commences the injection as the needle tip is simultaneously "stabbed" into the mucosa. This technique swiftly and accurately accesses the SM plane. The correct plane is confirmed by an immediate elevation of the mucosa. Ongoing injection without tissue elevation or intraluminal fluid escape indicates transmural placement of the needle tip with extramural injection. The needle is withdrawn slowly, and the tissue should elevate as the correct plane is reached. For wide field piecemeal EMR (>40 mm), a sequential inject and resect technique is preferred. Avoid elevating the entire lesion at the outset. This creates excessive tension within the cushion, limiting purchase of the snare and decreasing the size of sequential snare resections. Poor mucosal lifting indicates 1 of 3 things: invasive disease, SM fibrosis from previous resection attempts or aggressive biopsy, or SM fibrosis from repeated trauma due to prolapsing tissue, as can occur at the rectosigmoid. It is also more frequent in NG laterally spreading tumors, which have more SM fibrosis. Thus, a poorly lifting lesion is not an absolute contraindication for EMR; however, this aspect must be factored into the therapeutic process.Resection TechniqueLesions should be removed in as few pieces as safely possible. En bloc resection should be considered if technically possible for lesions up to 20 mm in the right colon and 25 mm in the left colon (particularly the rectum). En bloc and oligopiecemeal resections allow more accurate histologic assessment, creates fewer opportunities for error, and theoretically may reduce the risk of recurrence in comparison with lesions removed in multiple pieces. The first resection sets the scene for a successful procedure.•The lesion is placed in the 6 o'clock position.•Resect the most difficult and inaccessible portion first.•Include a 2–3 mm margin of normal mucosa.•Work sequentially from the point of first entry into the SM plane, using the edge of the defect as the base for snare placement, and aligning the snare along the defect margin to reduce the risk of adenoma islands (within the defect), which are difficult to subsequently remove.•If a large en bloc resection is planned, attempt to align the longitudinal axis of the snare with the longest axis of the lesion to maximize tissue capture. For lesions that have extended across the lumen, this may require impacting the snare tip then pivoting the body of the snare over the lesion.•Open the snare fully over the lesion, then angle down firmly with the up-down control onto the SM cushion while aspirating air to reduce colonic wall tension, decrease the mucosal footprint of the lesion, and maximize tissue capture.•Perform a staged snare closure, advancing the catheter to maintain the snare base at the lesion edge, while monitoring the lesion for "buckling" or loss of the margin, which requires snare repositioning.•Close the snare very tightly to exclude MP from the captured tissue. If using a spiral (serrated) snare, it is not possible to transect ensnared tissue of more than 10-mm diameter without the use of diathermy.•Take the snare for the final transection phase. The sensory feedback is invaluable to inform on the safety and efficacy of the excision. Safe tissue capture is confirmed by 3 maneuvers:•Assess the mobility of the ensnared tissue by moving the snare catheter quickly back and forth; it should move freely relative to the underlying colonic wall.•The snare should close fully with minimal "puckering" of the surrounding tissue. If concerned, the snare is partially opened and tented into the lumen to release the deeper tissue before repeat closure.•Transection should be fast; the snare is kept tightly closed while the foot pedal is depressed. With a microprocessor-controlled generator, using alternating cycles of high-frequency short-pulse cutting with more prolonged coagulation current, between 1 and 3 pulses, transect the tissue. A longer transection phase raises concerns of either MP entrapment or deeper neoplastic invasion. These features are not as reliable in the cecum or in retroflexion. In the right colon, we use "single taps" of the pedal, essentially cutting the lesion away from the colonic wall.The defect is washed and carefully examined after each resection for evidence of deep injury or residual adenoma (Figure 5). NBI is used to distinguish adenoma from diathermy artifact at the defect edges.Figure 5Interpretation of the post-EMR defect. (A) Nonstaining SM is seen adjacent to a relatively homogenous defect with a blue "mat" appearance. (B) SM chromoendoscopy: dye solution is irrigated over the surface of the nonstaining SM. The connective tissue is avid for the dye, and staining confirms the resection has taken place in the correct mucosal plane. (C) Post-EMR defect with uninjured MP visible, characterized by concentric transversely oriented parallel muscle fibers (as opposed to the "mat" appearance of stained SM). (D) A subtle injury to the MP is demonstrated, as evidenced by a white cautery ring within the defect ("mirror target sign"). (E) When all surrounding adenoma is removed, the defect is closed with endoscopic clips applied perpendicular to the long axis of the MP defect. (F) Despite the subtle injury, this is a full thickness perforation, which was confirmed histologically.View Large Image Figure ViewerDownload Hi-res image Download (PPT)All specimens are retrieved, pinned on cork, and sent in neutral formalin to pathology. Resection pieces where intramucosal cancer or submucosal invasive cancer (SMIC) was suspected endoscopically are identified and labeled separately. A close working relationship between the endoscopist and pathologist is essential. All SMIC must have the absolute depth of SMI reported, as well as high-risk features such as tumor grade and presence of lymphovascular invasion or an infiltrative or budding growth pattern.24Shimomura T. Ishiguro S. Konishi H. et al.New indication for endoscopic treatment of colorectal carcinoma with submucosal invasion.J Gastroenterol Hepatol. 2004; 19: 48-55Crossref PubMed Scopus (35) Google Scholar This allows an informed decision on adjuvant treatment to be made. All cases of SMIC should be discussed in a multidisciplinary team setting in the context of the patient's comorbidities, management goals, and expectations.Often the lateral margins of benign lesions removed by wide-field EMR cannot be histologically assessed as clear of adenoma. Ensuring that wide margins of normal tissue are taken and that defect edges are systematically examined at the completion of EMR eliminates the therapeutic relevance of this aspect.Special SituationsAnorectal junctionAMN at the anorectal junction require a modified approach due to the unique lymphovascular supply and innervation of the distal rectum and anus. We advocate prophylactic intravenous antibiotics for extensive resections due to the risk of systemic b
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