Gastric Endoscopic Submucosal Dissection

Gastric endoscopic submucosal dissection (ESD) is a technique of endoscopic resection that removes lesions by a free-hand dissection at the level of submucosal layer with injection solution, knives, and electrosurgical unit most suitable for larger gastric dysplastic lesions including early gastric cancer. This procedure was developed in Japan and currently prevailed because of the high curatively from cancer and low recurrence rate of dysplasia and cancer than conventional endoscopic mucosal resection (EMR). Since the stomach has its unique anatomical shape of sac, removal strategies are required for smooth and successful ESD tailored to a location of the lesion utilizing the benefit of gravity. Nowadays, wide variety of devices specific to the ESD procedure are available in the United States and setting of electrosurgical unit needs to be well understood to accomplish successful gastric ESD. Precise hemostasis or rather a prevention of active bleeding is also important because the anatomy of the gastric wall is proven to be rich in large blood vessels compared to other organs such as the esophagus and the colorectum. It is noted that ESD at the upper stomach has higher chance of experiencing arterial bleeding because of the rich arterial supply from the left gastric artery.

In this section, the indication, preparation, equipment, and procedural steps are described.

INDICATIONS

Indications of gastric ESD were established by the Japanese Gastric Cancer Association¹ and has been recently revised to expand the criteria.²,³ In the United States, no established indications have officially been endorsed; however, recent publication from American Gastroenterology Association suggested to adopt those indications. In essence, gastric ESD should be applied to the lesions without ulceration and are highly suggested to be limited to mucosa or
not to invade deeper than the shallow submucosal layer.² Another indication would be a large area of dysplasia (i.e., adenoma), which is unable to be removed en bloc by conventional techniques. Prior to ESD, the lesion should be assessed endoscopically for its extension and a depth of invasion to assess for possible submucosal invasion and also to rule out deeper invasion by endoscopic ultrasonography as needed. In cases when extension of the lesion is subtle and difficult to be determined, four-quadrant biopsies can be performed a few weeks prior to ESD to confirm its extent and to determine a lateral margin (i.e., a mapping biopsy). If the lesion is considered to fulfill the criteria described below, ESD may be chosen as a primary endoscopic treatment for gastric cancer and assess whether curative resection was achieved upon reviewing resected specimen. Patient’s performance status, comorbidity, and medications, especially an anticoagulant agent, are to be taken into an account when choosing the best treatment modality.

PREPARATION

Gastric ESD should be performed with informed consent from the patient explaining the specific concept of removal of mucosal and submucosal layer away from the muscle layer, ESD as an
alternative to EMR or surgery with certain benefits for a certain group of patients, and possible complications with slightly higher rates compared to EMR, possible incomplete attempt and termination of ESD due to a variety of factors complicating ESD procedure, and possible requirement of additional treatment such as surgery or multimodal therapy depending on the pathological stage after ESD. Patient is required to discontinue anticoagulation agents before gastric ESD according to the guideline. The patient required to be NPO after midnight as for regular upper endoscopic procedures. Patient and family member should be informed about the importance of follow-ups (i.e., postresection surveillance esophagogastroduodenoscopy (EGD) and cross-sectional imaging as indicated) and a possibility of additional surgical treatment as shown in the algorithm (Fig. 46.1). Prior to ESD, blood test (CBC, chemistry, and prothrombin time-international normalized ratio [PT-INR]), and EKG are preferable but not mandatory to assess patient’s condition prior to the procedure based on patient’s comorbidity.

ANESTHESIA AND PATIENT POSITION

Monitored anesthesia care or general anesthesia administered by anesthesia service is commonly used for gastric ESD. General anesthesia is recommended for a procedure that is expected to take long hours or for a patient with a risk of aspiration.⁴ General anesthesia is also to be considered for patients with large hiatal hernia or with a lesion at the gastroesophageal junction. Patient is positioned to the left lateral decubitus or may be on supine position. If the lesion is difficult to be accessed because it is located at incisura or lesser curvature of the body, then right lateral decubitus may be useful.