Large En-Bloc Resection for Colorectal Tumors Using Endoscopic Submucosal Dissection Method

Abstract

Background: Local recurrence has frequently occurred after endoscopic piecemeal mucosal resection for colorectal tumors. We have developed a novel endoscopic submucosal dissection method using Hook knife and Flex knife for the attempt of large en-bloc resection. We evaluated the effectiveness and complications of this method. Procedure: First, sodium hyaluronate solution is injected into the submucosal layer to separate the mucosa from the proper muscular layer. Sufficient lifting should be gotten for safe procedure. Next, the mucosa around the lesion is cut using Flex knife and Hook knife. Then, the submucosal fibers and vessels are dissected using Hook knife and Flex knife case by case. Hook knife is useful for difficult situation such as fibrous change. When the lesion is constricted sufficiently, the lesion is retrieved using large polypectomy snare. In this method, we can make the accurate histological assessment of the retrieved specimen and expect complete resection without residual tumor. Method: A total of 20 patients (20 lesions) who have large colorectal tumors underwent endoscopic submucosal dissection during the period from June 2000 to September 2004. We analyzed the clinicopathological characteristics of resected lesions, rates of complete en-bloc resection and complications. Result: 1) Location: lower rectum 1, upper rectum 5, recto-sigmoid 4, sigmoid colon 2, descending colon 1, transverse colon 4, ascending colon 1, cecum 2. 2) Macroscopic type: IIa 10, Is+IIa 7, IIa+IIc 3. 3) Size of lesion: Maximum which could be resected en-bloc is 65 mm and mean is 32.6 mm. 4) Histological type: submucosal invasive cancer 2, intramucosal cancer 8, tubular adenoma 10. 5) The rate of complete en-bloc resection was 85% (17/20). 6) Median procedure time 120 min (range 45-420). 7) The rate of complication: Micro-perforation 5% (1/20) (One who suffered from perforation recovered conservatively by immediate closure with endoscopic hemoclips.), Late bleeding 0% (0/20), High grade fever 10% (2/20). 8) The rate of local recurrence 0% (0/11). Conclusion: We successfully achieved large en-bloc resection in any location of colon and rectum using this novel endoscopic submucosal dissection method. Its complication was acceptable, because of no requirement of surgery.