Introduction: EMR is safe and useful technique for colorectal laterally spreading tumor(LST) and large sessile tumor. However it is difficult to perform the en bloc resection of the tumor>20 mm. Local recurrence was often observed for these lesions. Patients and Methods: The aim of study is to evaluate clinical outcome and feasibility of colorectal endoscopic submucosal dissection(ESD). 40 colorectal consecutive lesions(40 patients) were enrolled in this study. Indication criteria for colorectal ESD is VI pit pattern in magnification colonoscopy, and non-granular type(LST-NG) and mixed nodular type (LST-G(mix)) of LST, and large protruded lesion(>30 mm) in macroscopic type. ESD procedure: injection of grycerol and sodium hyarulonate acid, circumferential incision and submucosal dissection was performed by Flush knife. All cases performed by single colonoscopist(K.S) with CO2 insufflation. Massively submucosal invasive carcinoma(SM-M) was defined as over an invasion depth of 1000μm. Results: The average diameter of lesions was 31.2 ± 13.6. 4 lesions were located in the cecum, 2 in the ascending colon, 9 in the transverse colon, 2 in the descending colon, 6 in the sigmoid colon, 17 in the rectum. For macroscopic type, 20 lesions were LST-NG 14 LST-G(mix), 4 lesions Is, and 1 IIa+IIc. In pit pattern diagnosis, 33 lesions were type VI, 6 type IV, and 3 type IIIs. By histological examination, 17 intramucosal cancers, 11 slightly submucosal cancers (SM-S), 6 SM-M cancers, and 6 high grade adenomas. All lesions were lateral free margins, and 2 lesions of 6 SM-M cancers were positive of vertical margins. 2 lesions of 6 SM-M cancers were performed as the palliative therapy. The median operation time was 90 minutes (range,30-270 minutes), and the en bloc resection rate was 95% (38/40). Of 7 noncurative resection, 6 SM-M cancers, and 1 SM-S cancer with lymphatic (or vessel) invasion (or poorly differentiated component). 5 patients who were noncurative underwent surgery for lymph-node dissection except for 2 palliative lesions. No lymph node metastasis and residual tumor in resected specimen. With regard to complications, postoperative bleeding were observed 5% (2/40). Both lesions were located in the rectum and controlled by endoscopic hemoclipping without surgery and blood transfusion. No perforation and penetration were found. Conclusion: On the basis of results of this study, ESD with Flush knife and CO2 insufflation for LST and large protruded lesions provided safe and successful outcome. This ESD procedure provided a high en bloc resection rate and a low rate of complication.
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