Early diagnosis and resection are the primary means of treating gastric cancer. Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) have become one of the minimally invasive surgery modalities for early gastric cancer because of their characteristics of minimal injury, mild postoperative pain, and quick recovery and discharge. The prerequisites of radical resection for endoscopic treatment of gastric cancer include: 1) no lymph node metastasis; 2) sufficient safe margins in horizontal direction (extent of intra-mucosal infiltration) and vertical direction (depth of infiltration); 3) detailed pathological histological examination of the resected specimen can be performed after surgery. Ren Hongyu, Department of Gastroenterology, Wuhan Union Medical College Hospital
1 Indications for endoscopic treatment of intramucosal gastric cancer
The infiltrative growth of early gastric cancer includes horizontal direction (superficial infiltration) and vertical direction (deep infiltration and protrusion into the gastric lumen), superficial infiltration shows the size of lesions, while vertical infiltration shows the depth of gastric wall infiltration and lymph node metastasis, which determine whether endoscopic surgery can be performed to treat early gastric cancer. The prerequisites for radical resection of endoscopic treatment of gastric cancer are no lymph node metastasis, sufficient safe margins in the horizontal direction (extent of infiltration in the mucosa) and vertical direction (depth of infiltration), and detailed pathological histological examination of the resected specimen after surgery. The specific indications for endoscopic treatment are: all differentiated intramucosal carcinoma without lymph node metastasis without ulcerative erosion, differentiated type with ulcerative erosion below 3 cm in diameter and undifferentiated intramucosal carcinoma without ulcerative erosion below 2 cm in diameter; differentiated submucosal carcinoma without ulcerative erosion below 3 cm in diameter and undifferentiated submucosal carcinoma without ulcerative erosion below 2 cm in diameter.
2 Criteria for complete resection of gastric cancer by endoscopic pathology and histology
In recent years, the Committee on Endoscopic Treatment of Gastric Cancer of the Japan Society for Gastric Cancer Research has recommended the following criteria: 1) complete resection: negative histological section, no cancerous tissue remains on additional endoscopy and biopsy; 2) relatively incomplete resection: unknown or positive histological section, no cancerous tissue remains on additional endoscopy and biopsy without further treatment; 3) absolute incomplete resection: cancerous tissue remains on additional endoscopy and biopsy. histological examination with cancer tissue residue. Factors reported in the literature that influence the residual cancer cells include the size and location of the cancer foci; the type of cancer tissue; and the degree of diagnostic clarity of the boundaries of cancer infiltration.
3 Advantages and disadvantages of endoscopic therapy
Advantages: 1) less trauma, rapid recovery of organ function after surgery, mild pain and early departure from bed; 2) surgery under closed conditions, avoiding the influence of exogenous factors of open surgery; 3) treatment can be videotaped at the same time, providing visual image data for postoperative retreatment and academic communication. Disadvantages: postoperative pathological histological examination requires additional laparoscopic surgery or surgical radical surgery if the residual cancer at the severed end or the depth of cancer infiltration reaching below the submucosa layer is confirmed in cases.
4 Endoscopic treatment methods of gastric intramucosal carcinoma
1）Endoscopic mucosal resection is a method of removing the lesion by attracting or holding the lesion in the shape of polyp with forceps, and then removing the lesion with the help of collar.EMR treatment methods include exfoliation biopsy method, endoscopic double collar polyp removal method, local injection of hypertonic solution into the adrenal gland, transparent cap-assisted endoscopic mucosal resection and endoscopic suction mucosal resection method.
(2) Endoscopic submucosal dissection is a treatment method to remove the lesion by cutting the mucosa around the lesion and dissecting along the submucosal layer with a variety of endoscopes, which is suitable for dangerous cancer foci without lymph node metastasis in any part of the stomach and easy to operate. It includes IT knife, hook knife, Flex knife, triangle knife, needle knife, etc. ESD has the following advantages: 1) ESD can remove a wider range of lesions (>2 cm) and can perform pathological histological examination to evaluate whether there are cancer cells remaining at the cut edge, which has been applied to the treatment of early esophageal, gastric and colorectal cancer in Japan, etc.; 2) some ulcerative lesions can also be removed. Its operation time is longer and there is a risk of combined bleeding and perforation.
Ren Hongyu, Associate Professor, Department of Gastroenterology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology