Should We Mark the Margins Before EMR?

COMMENT

There are obvious limitations regarding the use of historical controls, and there were differences in techniques between the groups other than the use of margin marking. To the extent margin marking works, it would support the concept derived from recent studies of thermal ablation of the margin, ie, that most recurrences after piecemeal EMR using electrocautery originate from the defect margin. Personally, I find that after submucosal injection with a contrast agent, the actual margins of colorectal adenomas are easy to delineate. Furthermore, the absolute rates of recurrence in recent large trials of thermal ablation (2%-5%) are lower than that in this study of margin marking. Finally, we don’t know that performing the marking plus extending the resection out to the markings is any more efficient than thermal edge ablation. To the extent that this technique merits consideration as a rival to thermal ablation, a prospective randomized trial would be needed.