Insulated-tip knife endoscopic mucosal resection of large colorectal polyps unsuitable for standard polypectomy

Objectives: Endoscopic mucosal resection (EMR) has been shown to be safe and effective. En bloc resection is often not achieved using conventional EMR. Insulated-tip knife (It-knife) EMR has been recently proposed for early gastric cancer dissection and removal. This study was conducted to evaluate the safety and efficacy in obtaining en bloc resection with It-knife EMR of large colonic lesions not resectable with standard endoscopic techniques. Methods: A total of 29 patients (19 men, 10 women, mean age 67.5 yr, range 44-88) were included in the study. Lesions were considered not suitable for standard polypectomy because of large diameter (> 3cm), morphology, and/or position. Lesions were located in the rectum (N = 11), sigmoid: (N = 10), descending: (N = 4), transverse: (N = 2), and hepatic flexure (N = 2). After saline injection, circumferential incision and dissection of the lesions were attempted with the aim of achieving en bloc resection. Results: En bloc resection was achieved in only 55.1% of the lesions (16 out of 29 patients). In the remaining cases, resection was completed with a piecemeal technique. The median size of the en bloc resected specimen was 3 x 3.4 cm. Complications occurred in four patients (13.7%). At histopathology, 13 patients had low-grade dysplasia, 15 high-grade dysplasia. One patient had a tumor invading the submucosa and was submitted to surgery. Conclusions: It-knife EMR is a promising technique for attempting en bloc resection of large colonic polyps. Adequate training and caution are required because it can be associated with a higher complication rate than with other EMR modalities.