Endoscopic Excision of Synchronous Large Bowel Polyps in the Presence of Colorectal Carcinoma: is the Fear of Malignant Cell Implantation Justified? A Systematic Review of the Literature

Aim: A systematic review of the literature was performed to establish evidence to support the practice that in the presence of a colonoscopically diagnosed colorectal cancer immediate endoscopic excision of synchronous polyps should not be performed due to the risk of malignant cell implantation at the polypectomy site.

Method: A systematic literature search was performed using Medline, Embase and the Cochrane Central Register of Controlled Trials to identify studies comparing the rate of implantation of colorectal cancer cells in normal and damaged colonic mucosa and reports of colorectal cancer cells seeding into sites of damaged mucosa after polypectomy.

Results: No randomized controlled trials were identified. Three studies involving mammalian models of colonic mucosal damage were included. Pooling relevant results revealed that out of 59 exposed mammals only one developed tumour cell implantation at a site of colonic mucosal damage. This equates to a mammalian in vivo experimental risk of malignant cell implantation of 1.6%.

Conclusion: The topic of colorectal cancer seeding following endoscopic procedures has received little attention. This review suggests that in the presence of a proximal colonic carcinoma there is a negligible risk of malignant implantation if a more distal polyp is endoscopically excised.