An evaluation of colorectal endoscopic mucosal resection using high-magnification chromoscopic colonoscopy: a prospective study of 1000 colonoscopies.

Background and Study Aims: Endoscopic mucosal resection provides an alternative to surgery for resection of sessile and flat colorectal lesions. High-magnification chromoscopic colonoscopy may allow early detection and anticipate histological diagnosis by identifying colonic crypt patterns. The aim of the present study was to assess the efficacy and safety of en-bloc endoscopic mucosal resection with high-magnification chromoendoscopy in the management of sessile and flat colorectal lesions ≤20 mm. Patients and Methods: A single endoscopist using high-magnification chromoendoscopy prospectively examined 1000 patients attending for routine colonoscopy. Patients were selected for inclusion in the study if they were considered to be at high risk for underlying colorectal neoplasia or polyps. Within the study period, 1000 patients (29%) qualified for entry from a total of 3480 colonoscopies conducted in our institution. Endoscopic mucosal resection was carried out in appropriate flat and sessile lesions. Results: Endoscopic mucosal resection was carried out in 599 lesions. Complete histological resection was confirmed in 576 (96%). Perforation occurred in one patient (0.2%) and bleeding in 12 (2%). A total of 254 lesions (40%; excluding hyperplasia/metaplasia) were flat or depressed, and 374 (60%) were sessile. Fifty-eight flat lesions (23%) contained high-grade dysplasia or beyond, compared to 33 sessile lesions (9.0%; P= 0.001). After resection, 21 lesions were upgraded histologically, with 17 being defined as adenoma with high-grade dysplasia or beyond. Conclusions: This study confirms that flat adenomas and carcinomas occur in the West and demonstrates the malignant potential of such lesions, which can be managed successfully using endoscopic techniques. Endoscopic mucosal resection with high-magnification chromoscopy is a safe and effective form of treatment for sessile or flat colorectal lesions. Complete resection can improve the accuracy of histopathological diagnosis. However, colonoscopists require training in these procedures in order to improve the rate of colorectal cancer detection.