Optical assessment of scars after endoscopic mucosal resection of large colorectal polyps in a multicenter, community hospital setting: is routine biopsy still necessary?

Abstract

Background and study aims: Piecemeal EMR of large (≥20mm) non-pedunculated colorectal polyps (LNPCPs) is succeeded by a 6-month surveillance endoscopy to evaluate the post-EMR scar for recurrence. Data from expert centers suggest that routine tattoo placement and scar biopsies can be omitted, but data from community hospitals are lacking.

Patients and methods: In a post-hoc analysis of the STAR-LNPCP study (NTR7477), containing prospective data on 6-month post-pEMR scar assessments in 30 Dutch community hospitals (October 2019 to May 2022), the agreement between optical assessment and histological confirmation by routine biopsies was evaluated. Documentation of optical characteristics, imaging, and biopsies of the post-EMR scar were performed according to a standardized protocol.

Results: In 1277 post-EMR scar assessments, identification of the scar was achieved in 1215/1277 (95%). Tattoo placement did not influence scar identification. Scar biopsy was performed in 1050/1215 cases (86%). Recurrences were seen in 200/1050 cases (19%). There was a good agreement between optical assessment of recurrence and histological confirmation (Cohen's kappa 0.78 [0.73-0.83]). The NPV was 98% [97-99%] and the PPV was 74% [68-80%]. Higher false positive rate was seen after prior use of clips (11% vs. 5%, p=0.017). Dedicated endoscopists identified the scar more often (96% vs. 88%, p<0.001), and showed a lower optical recurrence miss rate (1%vs. 3%, p=0.111) compared to non-dedicated endoscopists.

Conclusion: Based on this multicenter community hospital study, routine tattoo placement and scar biopsies of the post-EMR scar can be omitted. Assessment of post-EMR scars by dedicated endoscopists is advised.