Is biopsying of post-endoscopic mucosal resection scars by general endoscopists a waste of time and money?

Recent studies have moved the needle away from performing routine biopsy of endoscopic mucosal resection (EMR) scars after piecemeal EMR of large (≥20 mm) nonpedunculated colorectal lesions [1] [2]. In this issue of Endoscopy, Meulen et al. describe the results of follow-up of 1050 lesions post-EMR that had both detailed endoscopic scar assessments and biopsies performed in 30 community hospitals in the Netherlands [3].

For my own practice, I am totally convinced that routine biopsying of optically normal-appearing EMR scars is finished. Biopsies can be reserved for unusual circumstances where there is uncertainty but very low suspicion of recurrence (certain recurrence or possible recurrence should be resected with intent to cure).

The study results suggest community endoscopists can accurately predict recurrence on EMR scars at first follow-up by endoscopic assessment alone. Based on this and other recent studies [1] [2] [3], taking routine biopsies adds little sensitivity for recurrence, is likely not cost-effective, and contributes unnecessarily to carbon emissions and plastic waste. Because the high accuracy of experts [1] [2] extends to community endoscopists [3], perhaps all routine biopsying of EMR scars can stop.

The general premise that the routine biopsying of EMR scars by experts can stop in the era of high definition colonoscopes, electronic chromoendoscopy, and magnification is readily accepted. Should we however be cautious before concluding that all community endoscopists, particularly those without training in EMR and optical biopsy, should stop doing these biopsies?

Let us first ask the question: what is a “community endoscopist”? In this study, 87% of post-EMR scar assessments were performed by 59 "dedicated" endoscopists trained in EMR and based in community hospitals [3]. The remaining 155 scar assessments were performed by 102 “nondedicated” endoscopists (equivalent to 1.5 scar assessments per nondedicated endoscopist). This is an insufficient number of scar assessments per nondedicated endoscopist to determine whether they are actually proficient and accurate in the optical assessment of scars. Before experts start relying on the referring doctors to perform EMR scar follow-up assessments, experts should ask whether their referrals come largely from endoscopists similar to this study’s dedicated endoscopists (EMR experts), or more like the nondedicated endoscopists.

The authors of this study suggest the nondedicated endoscopists also performed well, with a “miss rate” of only 3% compared with 1% for the dedicated endoscopists. The miss rate was defined as all histologically confirmed recurrences optically assessed as negative for recurrence divided by the number of inspected scars. Arguably, most of us would consider the miss rate to be the false-negative rate when recurrences are present. Using this definition, the overall recurrence miss rate for all study endoscopists was 7%. Although the fraction of recurrences missed by nondedicated endoscopists is uncertain, the numbers presented in the paper suggest the nondedicated endoscopists missed well over 10% of recurrences by optical inspection alone.

The current study also reports a high recurrence rate of 19%. Certainly with the very low recurrence rates now reported by some experts [4], missing recurrences is quantitatively less important; however, high recurrence rates, combined with unreliable optical scar assessments (a state of affairs unlikely to have been eliminated from worldwide endoscopy practice), could lead to poor outcomes for patients lost to follow-up after first surveillance. Remarkably high rates of patients being lost to follow-up after EMR of large nonpedunculated polyps continue to be reported [5]. In a study from our center spanning the era of both standard and high definition colonoscopes, we found among 65 histologic-only (negative optical assessment) recurrences, 11/41 (27%) had overt recurrence at next follow-up compared with only 2.7% with negative optical assessment and negative biopsies, but 37% of patients did not return for further follow-up [6]. A positive scar biopsy might encourage patients to comply with further follow-up and thus allow “late recurrence” to be identified [6], whereas reassurance based on ineffective optical assessment alone would falsely reassure patients not inclined to continue follow up.

There is also the clip artifact issue. Our center first described clip artifact [7], and later proposed a simple classification [8]. I regularly see gastroenterology fellows interpret clip artifact as recurrence until they become skilled in pit pattern interpretation. This anecdotal impression was confirmed by Meulen et al., who found the false-positive rate for predicting recurrence increased from 5% to 11% when clip artifact was present [3]. Considering that 64% of lesions were proximal and only 20% of EMR sites were clipped, clip artifact could be quantitatively a substantially more important cause of false positives in centers where all large proximal nonpedunculated EMR defects (lesions removed by electrocautery) are closed with clips. This could be risky if general endoscopists with limited experience use thermal treatments to resect clip artifact, rather than taking cold biopsy samples, until they learn its appearance. In my anecdotal experience, a further advantage of cold biopsies that include biopsy of the clip artifact is that, at subsequent follow-up, the clip artifact is less prominent and therefore less confusing.

For my own practice, I am totally convinced that routine biopsying of optically normal-appearing EMR scars is finished. Biopsies can be reserved for unusual circumstances where there is uncertainty but very low suspicion of recurrence (certain recurrence or possible recurrence should be resected with intent to cure). In some cases, I might still take cold biopsies to safely remove extensive clip artifact, so it will be less confusing in future, when I know that subsequent follow-ups will be performed by the patient’s local endoscopist (a good reason to biopsy? who knows?).

Perhaps whether community endoscopists should abandon performing scar biopsies depends on what is meant by “community endoscopists.” Endoscopists practicing in community hospitals who are experts in EMR, like the endoscopists who performed most of the EMR assessments in the study by Meulen et al., is not the picture I carry of “community endoscopists,” and does not represent the skill set of most endoscopists in either community or academic practice in most regions I have encountered. It may take another trial performed among true general endoscopists to understand how they perform in optical assessment of EMR scars, or what instruction and training tools are needed for them to perform well. Until we know the masses have caught up with the experts, whether to take cold biopsies of EMR scars at first follow-up should be considered in the context of local recurrence rates, and the training and confidence of the endoscopist performing follow-up.

Publication History

Article published online:
14 April 2025

• References

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