Recurrence following piecemeal endoscopic mucosal resection of 10–20-mm polyps: an underappreciated problem with a simple solution?

Endoscopic mucosal resection using an electrosurgical snare (hot EMR) is firmly established as the standard of care for the management of large (≥20 mm) adenomatous nonpedunculated colorectal polyps (NPCPs). While the optimal approach for medium-sized (10–19 mm) NPCPs is still debated, the 2024 European Society of Gastrointestinal Endoscopy (ESGE) guidelines support the use of hot polypectomy or hot EMR over cold snare polypectomy [1]. This is mainly due to the higher rates of en bloc resection that can be obtained, which is an important consideration in community settings where optical diagnosis may not be sufficient to exclude submucosal invasive cancer. In all cases, complete removal is crucial to reducing recurrence and minimizing the subsequent risk of colorectal cancer.

“This much-needed study confirms that recurrence is a prominent issue for medium-sized nonpedunculated colorectal polyps after hot-snare piecemeal EMR.”

Although data on local recurrence following hot EMR of medium-sized polyps are limited, it is likely an underappreciated problem. Early surveillance is not mandated in most guidelines, and post-resection scars may not be detectable to assess for local recurrence. As a result, most studies to date have used incomplete resection rates as a proxy. A recent meta-analysis found an overall incomplete resection rate of 18.5% for 10–19-mm polyps removed by EMR [2]. In the few studies where true local recurrence has been examined, rates are lower than incomplete resection rate estimates, but remain concerningly high. A single-center retrospective Portuguese study by Lima Capela et al. examined local recurrence in 124 patients at 3–6 months after hot piecemeal EMR (pEMR) of 10–19-mm lesions, 80.6% of which were adenomas. The local recurrence rate was 10.5% overall and 12% for adenomas. Of note, all recurrences occurred in 15–19-mm lesions [3].

If recurrence is an issue, then the question is how do we reduce it? One solution may be borrowed from the data on EMR for large (≥20 mm) NPCPs. For these, post-EMR recurrence rates once exceeded 25%. However, the introduction of margin thermal ablation (MTA) to the post-EMR defect has been revolutionary. In an international multicenter study, MTA with snare-tip soft coagulation was shown to significantly reduce the 6-month recurrence rate to 1.4% [4], and in a long-term recurrence study, the effect was durable to at least 2 years [5]. A recent meta-analysis has also demonstrated MTA to be highly effective for lesions ≥15 mm [6]. This raises the question as to whether recurrence could be reduced if MTA is utilized for 10–19-mm lesions.

In this issue of Endoscopy, Mass et al. investigate these issues in a multicenter retrospective study examining early recurrence following hot-snare pEMR of 10–20-mm NPCPs. Between 2014 and 2021, 103 endoscopists from five hospitals in the Netherlands resected 426 lesions [7]. Around 20% of scars were tattooed at the time of resection. Endoscopist experience varied and junior, senior, nurse, and expert endoscopists were involved at both teaching and non-teaching hospitals.

Early surveillance colonoscopies (3–9 months post-EMR) revealed a recurrence rate of 8.2%. The post-EMR scar was identifiable in 61.5% of cases and in these instances, recurrence was confirmed in 13.4%. MTA with snare-tip soft coagulation was performed in 15.7% of cases and argon plasma coagulation in 5.9%. Lesions treated with MTA had a recurrence rate of 4.3% compared with 9.3% for those without MTA (odds ratio 0.44; 95%CI 0.15–1.29; P = 0.13). Although this difference did not reach statistical significance, the analysis is likely underpowered. The study also examined the risk of metachronous advanced neoplasia at the second surveillance colonoscopy in patients where the early surveillance colonoscopy was clear. Metachronous advanced neoplasia was present in approximately 10% of patients at a median of 30 months, and surprisingly over 2/3 of this was attributed to local recurrence.

This much-needed study confirms that recurrence is a prominent issue for medium-sized NPCPs after hot pEMR. When interpreted in combination with the Lima Capela et al. study, and assuming that the true local recurrence rate sits somewhere between the overall and scar-identified rate, it appears that early recurrence is likely to occur in approximately 10%–12% of cases. Worryingly, late recurrence is also common and although all recurrence was diminutive and low grade, in a larger cohort there is a risk that cancer may occur in this recurrent tissue. Contemporary estimates suggest that around 7% of post-colonoscopy colorectal cancer is attributed to incomplete resection, so mitigating this risk is essential [8].

The majority of 10–19-mm NPCPs can be removed en bloc (80%), and data from large NPCPs ≥20 mm demonstrate that rates of local recurrence after en bloc EMR is under 2% [3] [9]. This suggests that the local recurrence risk resides in piecemeal resection. A recurrence rate of 10%–12% for hot pEMR of 10–19-mm NPCPs is similar to the historical rate for large NPCPs ≥20 mm prior to the introduction of MTA, and suggests that early surveillance should be recommended. British surveillance guidelines recommend a “site check” at 2–6 months for 10–19-mm lesions where “histological completeness of excision cannot be determined” (i.e. piecemeal) [10]. US guidelines acknowledge the risk of incomplete resection, but do not make a distinction for lesions resected en bloc or piecemeal, suggesting follow-up for all lesions at 3 years. ESGE guidelines in 2013 did suggest early follow-up for lesions ≥10 mm resected piecemeal, but this advice was rescinded in 2020 due to an absence of data [11]. Perhaps now, guidelines should re-examine these recommendations and consider early surveillance for the minority of lesions that are resected piecemeal.

Increasing surveillance to detect and treat recurrence is inconvenient for patients and costly for health systems, so the other approach is to minimize recurrence in the first place. MTA has transformed recurrence risk after pEMR for lesions ≥20 mm. Although the Maas et al. study was underpowered to show a difference in recurrence rates with MTA, the absolute rates of recurrence were halved, which is similar to the effect seen in ≥20-mm lesions. MTA is quick to perform, does not require device exchange, and incurs no additional cost. Moreover, it is safe, with no increase in post-polypectomy syndrome, perforation, or bleeding [4]. Lesions in the 10–19-mm size range are typically resected in community settings and few are referred for expert resection, so techniques need to be accessible and easy to apply. If recurrence can be reliably reduced to negligible rates, then early surveillance may not be required and 3-year follow-up can be safely recommended.

This study underscores the critical importance of reducing recurrence. First and foremost, the importance of a proper hot EMR technique cannot be understated [12]. This should begin with careful cleaning and optical assessment of the NPCP. High-definition white-light, virtual chromoendoscopy, and magnification, if available, should all be utilized to characterize the NPCP. If deemed to be a 10–19-mm adenoma without concerns for submucosal invasive cancer, then en bloc resection should be favored, but piecemeal hot EMR is also appropriate. Care should be exercised to resect all visible adenoma. If piecemeal EMR has been performed then consideration should be given to MTA, especially for lesions over 15 mm. The benefit of a systematic approach to EMR was demonstrated in a study where an e-learning module followed by a 2-day in-person course resulted in local recurrence dropping from 25% to 13% for large NPCPs [13].

Recurrence after EMR of medium NPCPs is a significant concern and early surveillance may be worth considering following piecemeal resection. Although MTA is not routinely recommended for lesions <20 mm, its potential benefits in reducing recurrence warrant further exploration. In the meantime, clinicians should carefully assess resection margins, consider MTA, and closely assess post-EMR defects. By reducing recurrence, MTA could improve patient outcomes and optimize surveillance strategies, making it safer to adhere to the longer follow-up intervals currently recommended in the guidelines.

Publication History

Article published online:
20 May 2025

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