Resection margin involvement after endoscopic excision of malignant colorectal polyps: definition of margin involvement and its impact upon tumour recurrence.

Definitions of margin involvement for endoscopically removed malignant polyps in the colon and rectum vary between health-care systems, but a 1-mm clearance is widely used in Europe and North America. Our results suggest that a 1-mm margin is unnecessary and should be replaced by a definition based on tumour at the margin or within coagulation artefact at the polyp base.