8 minute read
EMR or ESD?
Alexander Schlachterman, MD Associate Professor of Medicine Director, Third Space Endoscopy, Section of Advanced Endoscopy Thomas Jefferson University Hospital
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New and improved technologies and techniques in endoscopy have allowed management of complex mucosal lesions without needing to resort to surgery. These are termed “organ-sparing” procedures and can lead to outstanding curative results while in many cases avoiding surgical intervention. There is an impressive safety record of the procedures as well.
Advanced mucosal resection techniques include endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD). The general difference is that ESD is typically done to ensure an en bloc resection of the mucosal lesion. With an en bloc technique, resection margins can be accurately determined, so it is ideal for early mucosal cancers for which successful ESD can be curative. EMR can deliver en bloc resection only with smaller lesions, and larger lesions have to be removed in a piecemeal fashion.
Both EMR and ESD started in Japan to manage early gastric cancers. Development of techniques and devices to accomplish EMR and ESD was soon applied to mucosal lesions throughout the GI tract. Expansion of ESD in the West has been considerably slower than in Asia, mainly because of the much lower incidence of early superficial spreading gastric cancer. In the West, the colon is most often the target of EMR and ESD procedures. In the United States, ESD is now performed at major tertiary medical centers.
A brief review of GI applications for esophageal, gastric and colorectal ESD is timely as more United States centers are offering these services.
Esophagus
The European Society for Gastrointestinal Endoscopy (ESGE) recommends endoscopic en bloc resection for superficial esophageal squamous cell cancers (SCCs), excluding those with obvious submucosal involvement. Although SCC is seen in other parts of the world more than the United States, it can be treated with en bloc EMR if the lesion is smaller than 10 mm. However, the ESGE recommends ESD as the first option, mainly to provide an en bloc resection with accurate pathology staging and to avoid missing important histological features. The American Gastroenterology Association (AGA) recommends ESD as the primary modality for treatment of squamous cell dysplasia and cancer confined to the superficial esophageal mucosa. Any degree of submucosal invasion caries an increased risk of lymph node metastasis and alternative/additional therapy should be considered.
The ESGE recommends endoscopic resection with a curative intent for visible lesions in Barrett’s esophagus. ESD has not been shown to be superior to EMR for excision of mucosal cancer, and for that reason EMR should be preferred for smaller lesions. ESD may be considered for en bloc resection in selected cases, such as larger lesions, poorly lifting tumors, and lesions at risk for submucosal invasion. Recent AGA best practice guidelines state that ESD may be considered in selected patients with Barrett’s esophagus with the following features: large or bulky area of nodularity, lesions with a high likelihood of superficial submucosal invasion, recurrent dysplasia, endoscopic mucosal resection specimen showing invasive carcinoma with positive margins, equivocal preprocedural histology, and intramucosal carcinoma.
Stomach
The ESGE recommends endoscopic resection for the treatment of gastric superficial neoplastic lesions that possess a very low risk of lymph node metastasis. EMR is an acceptable option for lesions smaller than 10 – 15 mm with a very low probability of advanced histology (Paris 0-IIa). However, the ESGE recommends ESD as treatment of choice for most gastric superficial neoplastic lesions larger then 10-15mm. The safety and feasibility of ESD for early gastric cancer is well established. The absolute indications for curative endoscopic resection include moderately or well-differentiated nonulcerated mucosal lesions that are ≤2 cm in size. Recent expanded indications for gastric ESD include moderately and well-differentiated superficial cancers that are >2 cm, lesions ≤3 cm with ulceration or that contain early submucosal invasion, and poorly differentiated superficial cancers ≤2 cm in size. The risk of lymph node metastasis for these extended indications is higher but remains acceptably low. Many of the patients undergoing ESD with expanded indications have comorbid conditions precluding surgical intervention.
Colorectal
The majority of colonic and rectal superficial lesions can be effectively managed with curative intent by standard polypectomy and/or by EMR. ESD can be considered for removal of colonic and rectal lesions with high suspicion of limited submucosal invasion. Submucosal invasion is suggested by depressed morphology and irregular or nongranular surface pattern, particularly if the lesions are larger than 20 mm. ESD can be considered for colorectal lesions that otherwise cannot be optimally and radically removed by snarebased techniques.. Accumulating evidence has shown that the majority of colorectal neoplasms without signs of deep submucosal invasion or advanced cancer can be treated by advanced endoscopic resection techniques. Colorectal neoplasms containing dysplasia confined to the mucosa have no risk for lymph node metastasis and endoscopic resection should be considered as the criterion standard.
Large (>2 cm) colorectal lesions frequently require piecemeal removal when EMR is performed, and this can be associated with rates of recurrent neoplasia up to 20%. ESD enables higher rates of en bloc resection and lower recurrence rates for these lesions. Patients with large complex colorectal polyps should be referred to a high-volume, specialized center for endoscopic removal by either EMR or ESD.
Duodenum
ESD in the duodenum is associated with an increased risk of intraprocedural perforation and delayed adverse events even in the hands of experts. It has been strongly suggested that endoscopists in the United States refrain from performing duodenal ESD during the early phase of their ESD practice. EMR is the preferred treatment of adenomatous lesions of the duodenum. Duodenal EMR requires particular expertise in mucosal resection due to anatomic factors and increased risk of perforation and post-polypectomy bleeding, which can be as high as 15%. General knowledge for EMR and ESD referral
Avoid practices that may induce submucosal fibrosis which can prevent complete removal by EMR and/or ESD. These include tattooing in close proximity or beneath a lesion for marking as the tattoo can induce significant submucosal fibrosis and make future resection very difficult. It is impressive how far tattoo can track, so the tattoo should ideally be on the opposite wall of the colon. In addition, aggressive biopsy or partial snare resection of a portion of a lesion can make subsequent resection complex. If the lesion will be referred to an advanced endoscopist for management, biopsy may not be needed at all. However, if biopsies are done, they should be limited and not very deep.
Careful assessment of the “pit pattern” of a lesion can be useful in determine the optimal approach for resection of a mucosal lesion. Contrast or reaction chromoscopy along with high definition and magnification endoscopy is prevalent in Asia. However, most US endoscopists are not trained in this technique, and in addition, less than perfect interobserver agreement in pit pattern evaluation can be a limitation of its use. It is hoped that artificial intelligence assessment of these features will be useful for endoscopists to make a more accurate assessment at the time of initial endoscopy. When in doubt for larger lesions, it is probably best to not attempt resection, and instead refer the patient to an expert.
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Risks of EMR and ESD, and technical considerations
The risks of EMR are well known, and include perforation (which is very rare), and delayed bleeding. ESD has a higher perforation rate; however, most of these perforations, when they occur, are seen immediately usually during the dissection, and can be successfully managed without serious sequelae.
ESD requires special training and should be done by a practitioner who subspecializes in complex mucosal resection. ESD can be extremely time consuming, with procedure lengths not uncommonly more than 2 hours. It can be hard to block time on an endoscopy schedule to accommodate these procedures! In general, it is usually sufficient to have one ESD specialist on staff at a major medical center. This contributes to better outcomes and shorter procedure times as that individual grows in their skill set. Clearly, ESD is not something that can be picked up with a weekend course.
As expertise with ESD grows in the West, more mucosal lesions will be managed with this approach. However, the EMR technique is still adequate for the majority of colonic lesions. An exception might be for larger rectal lesions, because en bloc resection allows the best T staging as well as resection margin evaluation. For example, if a large rectal polyp is removed with piecemeal EMR, and then later found to have cancer on histology, the completeness of resection cannot be easily determined. An ESD approach, on the other hand can allow an accurate determination of completeness of resection. As one can see, the stakes of incomplete resection of an early cancer of the rectum are much higher than higher in the colon, as a proctectomy is a much more complex and morbid procedure than a hemicolectomy.
REFERENCES:
Pimentel-Nunes P, Libânio D, Bastiaansen BA, Bhandari P, Bisschops R, Bourke MJ, Esposito G, Lemmers A, Maselli R, Messmann H, Pech O. Endoscopic submucosal dissection for superficial gastrointestinal lesions: European Society of Gastrointestinal Endoscopy (ESGE) Guideline–Update 2022. Endoscopy. 2022 May 6.
Draganov PV, Wang AY, Othman MO, Fukami N. AGA institute clinical practice update: endoscopic submucosal dissection in the United States. Clinical Gastroenterology and Hepatology. 2019 Jan 1;17(1):16-25.
Ishihara R, Arima M, Iizuka T, Oyama T, Katada C, Kato M, Goda K, Goto O, Tanaka K, Yano T, Yoshinaga S. Endoscopic submucosal dissection/endoscopic mucosal resection guidelines for esophageal cancer. Digestive Endoscopy. 2020 May;32(4):452-93.
