Post written by Lobke Desomer, MD, from Westmead Hospital, Department of Gastroenterology and Hepatology, Sydney, NSW, Australia.
Endoscopic mucosal resection (EMR) is an increasingly used, safe, and effective technique for the removal of large laterally spreading colorectal lesions ≥20 mm. At present, EMR is seen as a 2-stage procedure with the first surveillance colonoscopy at 4 to 6 months used to ensure detection and adequate treatment of residual or recurrent adenoma (RRA), which occurs in 10 to 20% of LSLs. Currently, there are no guidelines available on how to assess the post-EMR scar. In this manuscript, we have described a simple, standardized post-EMR scar assessment protocol using high-definition white light (HD-WL) and narrow band imaging (NBI) to accurately detect RRA.
Figure 5. Two examples of flat recurrence not noticeable under high-definition while light (A, B). A clear transition point (arrows) where a normal vascular or pit pattern turns into a neoplastic one is visible under examination with narrow-band imaging (C, D).
We demonstrated that endoscopic detection of RRA has a very high specificity and that applying NBI substantially increases sensitivity as opposed to HD-WL alone. This approach allows endoscopists to confidently predict a scar to be clear of any RRA, but it also allows targeted biopsies of areas of concern and, moreover, real-time treatment of RRA. This finding has the potential to change practice, improve clinical outcomes, and reduce costs.
This imaging protocol relies on the simple method of identifying a transition point in a relatively homogenous non-neoplastic pit pattern. This was best achieved with NBI, especially for flat RRA. Sensitivity and specificity for endoscopic assessment were 93.3% and 94.1%, respectively; PPV and NPV were 75.7% and 98.6%, respectively, indicating it rarely misses RRA but tends to over call its presence. Despite the risk of over treatment, this is an acceptable trade off because non-treatment of RRA risks extensive recurrence at subsequent follow-up or, worse, interval cancer.
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