Endoscopic Mucosal Resection and Endoscopic Submucosal Dissection for Esophageal Dysplasia and Carcinoma




Advanced cancer in the esophagus is a serious and fatal disease that invades locally to deeper layers of the esophageal wall with significant risk of nodal metastasis and invasion of adjacent organs. One reliable method of avoiding this is to detect lesions at an early stage of esophageal cancer and then to resect them locally. A major advantage of endoscopic local resection is to recover a specimen for histopathologic analysis, which helps to make a clinical decision for further therapy. Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) have already been established as the techniques of endoscopic local resection. EMR includes strip-off biopsy, double-channel techniques, cap technique, EMR using a ligating device, and so on. ESD is a newly developed technique in which submucosal dissection is carried out using an electrocautery knife to acquire a single-piece specimen.


Advanced cancer in the esophagus is a serious and fatal disease that invades locally to deeper layers of the esophageal wall with significant risk of nodal metastasis and invasion of adjacent organs. One reliable method of avoiding this is to detect lesions at an early stage of esophageal cancer and then to resect them locally. A major advantage of endoscopic local resection is to recover a specimen for histopathologic analysis, which allows one to make a clinical decision for further therapy. Once cancer invades into the submucosal layer and/or permeates into the lymphatic vessel, additional surgery or chemoradiotherapy becomes necessary if there is to be any hope for a complete cure from the disease. This is because there is 0% risk of lymph node metastasis for cancers limited to the mucosa, but there is a 16% to 22% risk for cancers that extend into the submucosa. Tumor biology may also be important because well-differentiated carcinomas usually involve the mucosa only (93%). By comparison, only 74% and 23% of moderately and poorly differentiated carcinomas, respectively, are confined to the submucosa. Indication for endoscopic local resection of esophageal neoplasia is a superficial lesion of the esophagus with no risk of lymph node metastasis. From histologic analysis of the surgically resected specimen, mucosal cancer (high-grade intramucosal neoplasia) generally has an extremely low risk of lymph node metastasis. Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) have already been established as techniques of endoscopic local resection. EMR includes strip-off biopsy, double-channel techniques, cap technique, EMR using a ligating device, and so on. ESD is a newly developed technique in which submucosal dissection is carried out using an electrocautery knife to acquire a single-piece specimen.


In this article, the EMR-cap technique and ESD using a triangle-tip knife are introduced, both of which were devised by the authors. The cap technique is a fast and easy procedure to perform, and it is mostly applied to a relatively small lesion (around 1 cm). The triangle-tip (TT) knife is applied to a larger lesion for a one-piece resection.


Principles of endoscopic local resection


The esophageal wall basically consists of 2 major components: the mucosal layer and the muscle layer. Embryologically, the mucosa develops from the endoderm, and the muscle layer is derived from the mesoderm. These 2 components are attached to each other by the loose connective tissue of the submucosa and can be easily separated by an external force. For this reason, it is possible to resect only the mucosa, leaving the muscle layer intact. However, the esophageal wall is just 4 mm thick, and therefore special management is necessary to create a technically safe working space between the mucosa and muscle layer. Saline injection into the submucosal layer is the easiest and most cost-effective technique for separating the 2 layers. Lifting of the mucosal surface is always observed after correct submucosal injection of the saline. After a sufficient volume of saline has been injected, the mucosa, including the target lesion, can be safely captured with the cap or can be dissected with an electrocautery knife.




EMR using a cap-fitted endoscope


The steps involved in EMR using a cap-fitted endoscope (EMR-C) are described in the following sections. “Cap” here refers to an attachment on the distal tip of the forward-viewing endoscope, and it is made of a transparent plastic material.


Preparation


In preparation for the EMR-C procedure, a cap is attached to the tip of the forward-viewing endoscope and is fixed tightly with an adhesive tape. For the initial session of EMR in the esophagus, an obliquely cut large-capacity cap with a rim (Olympus MAJ297, Tokyo, Japan; Fig. 1 A) is most commonly used by fixing it onto the tip of the standard size endoscope. By using this large cap, a large sample can be obtained. For trimming a residual lesion, if necessary, a straight-cut medium-size cap with a rim (Olympus MH595, see Fig. 1 B) is appropriate. All of the items needed for the EMR-C procedure are present in an EMR kit (Olympus).




Fig. 1


Distal attachment “cap” for EMR. ( A ) Large, oblique cap with rim; outer diameter, 16.5 mm. This large cap is applied to a first capture during the EMR-C procedure. Around 2 cm of mucosa can be resected en bloc. ( B ) Medium, straight cap with rim; outer diameter, 13.5 mm. This cap is used to trim the lesion. Approximately 1 cm of mucosa can be resected en bloc.


Markings


The mucosal surface that surrounds the margin of the lesion is carefully marked by the tip of the snare wire. Markings are positioned 2 mm away from the actual lesion margin. This is important because the appearance of the lesions and its margins may become dramatically distorted and difficult to recognize after submucosal injection (see later discussion). The image enhancement produced by chromoendoscopy disappears within a couple of minutes. On the other hand, marking by electrocautery lasts longer, which helps easy recognition of lesion margin, especially for a flat lesion.


Injection


A diluted epinephrine/saline solution (0.5 mL of 0.1% epinephrine solution plus 100 mL of normal saline) is injected into the submucosa with an injection needle (23 gauge; tip length, 4 mm). Puncturing the target mucosa at a sharp angle is the most important key to avoiding transmural penetration of the needle tip ( Fig. 2 B). The total volume of injected saline depends on the size of the lesion, but it is necessary to inject enough saline to lift up the whole lesion. Usually, more than 20 mL epinephrine/saline is injected. Normal mucosa that is distal to the lesion is first punctured. When saline is accurately injected into the submucosal layer, lifting or bulging of the mucosa is always observed in any part of esophageal wall (see Fig. 2 ).




Fig. 2


( A ) Endoscopic view. Lesion with nodular surface was easily identified with regular endoscopy. Surface irregularity suggests that invasion of this lesion may be submucosal. ( B ) Schematic drawing of submucosal injection. The cap is premounted onto the endoscope. An injection needle is passed through the working channel of the endoscope. When injection is performed appropriately into the submucosal layer, lifting of the mucosa (including the target lesion) can be achieved. The distal part of the lesion is lifted first. This ensures that the lesion is always kept in endoscopic view. ( C ) Prelooping of the snare wire. Snare wire is fixed to the rim of the distal attachment cap. ( D ) After creating the preloop, target mucosa is captured inside the cap. Full endoscopic suction draws the lifted mucosa inside the cap. Large-volume injection of saline avoids muscle involvement. ( E ) The lesion was caught by endoscopic suction inside distal attachment cap. ( F ) Snare wire is closed tightly. The captured mucosa looks like a pseudopolyp, which is resected by electrocautery. Coagulation current is the best option for achieving complete hemostasis. ( G ) Pseudopolyp that includes cancerous lesion was resected by electrocautery. This process is similar to conventional polypectomy. ( H ) Artificial ulcer was induced. Submucosal layer was observed as blue layer. ( I ) Resected specimen. A 9×5-mm lesion was resected in a single piece with enough lateral margin of nonneoplastic mucosa. ( J ) Esophageal squamous cell carcinoma. Cancer invaded deep submucosal layer (T1b). Invasion depth from lamina muscularis mucosa was 397 μm. In this case, cancer infiltration depth was SM2, which has a potential risk of approximately 40% lymph node involvement. This patient refused to receive surgery. Chemotherapy was carried out several times.


Prelooping of the Snare Wire


A specially designed small-diameter snare (outer diameter,1.8 mm; Olympus SD-7P) is essential for the prelooping process. The snare wire is fixed along the rim of the cap. To create prelooping conditions, moderate suction is first applied to the normal mucosa to seal the outlet of the cap, and the snare wire that passes through the endoscope instrument channel is then opened. The opened snare wire is fixed along the rim of the cap, and the snare’s outer sheath sticks up to the rim of the cap (see Fig. 2 C). This completes the prelooping process for the snare wire.


Suction of the Target Mucosa


The prelooping position is maintained as the endoscope is brought near the target mucosa. The target mucosa, including the lesion, is fully sucked inside the cap (see Fig. 2 D, E) and is strangulated by simple closing of the prelooped snare wire. At this moment, the strangulated mucosa looks like a snared polypoid lesion (see Fig. 2 F, G).


Resection


The pseudopolyp of strangulated mucosa is cut using blended-current electrocautery. The resected specimen can easily be taken out by keeping it inside the cap without using any grasping forceps. The smooth surface of the proper muscle layer is observed at the bottom of the artificial ulcer (see Fig. 2 H).


Additional Resection


If additional resection is necessary to remove the residual lesion completely, all of the processes, including saline injection, should be repeated step by step. The injected saline usually infiltrates and disappears within a few minutes at the initial injection site, so that it no longer acts as a cushion between the mucosa and muscle layer. Repeated saline injection is therefore necessary to reduce the risk of muscle involvement during the procedure.




EMR using a cap-fitted endoscope


The steps involved in EMR using a cap-fitted endoscope (EMR-C) are described in the following sections. “Cap” here refers to an attachment on the distal tip of the forward-viewing endoscope, and it is made of a transparent plastic material.


Preparation


In preparation for the EMR-C procedure, a cap is attached to the tip of the forward-viewing endoscope and is fixed tightly with an adhesive tape. For the initial session of EMR in the esophagus, an obliquely cut large-capacity cap with a rim (Olympus MAJ297, Tokyo, Japan; Fig. 1 A) is most commonly used by fixing it onto the tip of the standard size endoscope. By using this large cap, a large sample can be obtained. For trimming a residual lesion, if necessary, a straight-cut medium-size cap with a rim (Olympus MH595, see Fig. 1 B) is appropriate. All of the items needed for the EMR-C procedure are present in an EMR kit (Olympus).


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Sep 12, 2017 | Posted by in GASTOINESTINAL SURGERY | Comments Off on Endoscopic Mucosal Resection and Endoscopic Submucosal Dissection for Esophageal Dysplasia and Carcinoma

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