Endoscopic submucosal resection: a new addition to our toolbox?

Various techniques are available to interventional endoscopists for the resection of colorectal lesions. The most common is endoscopic mucosal resection (EMR), which involves submucosal injection and snare resection of the lesion, either in a piecemeal fashion or en bloc, depending on the size and the morphology of the lesion. In underwater EMR (UEMR), the target lesion is submerged in water, and the resulting pseudopolyp is then resected with a standard snare [1]. Endoscopic submucosal dissection (ESD), in contrast to EMR and UEMR, is a more tedious procedure and requires a high level of expertise. In the hands of nonexperts, ESD is time consuming and may have higher complication rates, especially in the colon [2]. The advantages of these resection techniques depend strongly on the setting and indication for which each is applied. Piecemeal EMR remains the most commonly used technique and can be correctly applied to lesions with a low risk of submucosal invasive cancer, such as granular-type lesions. The major drawback of piecemeal EMR is the risk of recurrence, which can be as high as 20 % [3]. UEMR, on the other hand, is faster and, in some cases, more efficient than standard EMR in terms of R0, en bloc, and recurrence rates but remains to be adopted on a broad scale [4]. In expert hands, colorectal ESD produces excellent en bloc resection rates with low recurrence rates [5]; however, the tortuous nature of the colonic lumen and the thin wall, especially in the cecum, limit its widespread application in Europe.

“A possible role of endoscopic submucosal resection could be, for example, in the resection of colonic lesions larger than 30 mm and with signs of potential submucosal invasive cancer, where en bloc resection is desirable. In such cases, EMR and underwater EMR will be limited by their en bloc resection potential, while ESD expertise may not be available.”

In the study by Metter et al. in this issue of Endoscopy, an interesting new concept, endoscopic submucosal resection (ESR), for the resection of colorectal lesions is presented along with data from a multicenter case series [6]. ESR is a two-step procedure that includes the circumferential mucosal incision using the FARIn U device followed by en bloc resection using the FARIn snare (MICRO-TECH Europe GmbH, Düsseldorf, Germany). FARIn is an acronym for “Flat Adenoma Resection Instrument,” a snare specifically designed to enhance deep resection of the submucosa. The snare design and resulting deep submucosal resection are important aspects differentiating ESR from hybrid ESD or precutting EMR procedures. The novel snare does not cut along its entire circumference; instead, a greater part of the snare is insulated, and only the most distal portion of the snare is a high frequency surgical cutting wire. The concept behind this design, according to the authors, is that when the snare is pushed toward the muscle layer during the cutting phase, a homogeneous cutting plane close to the muscle layer is produced, thereby liberating more submucosal tissue than standard EMR.

In a multicenter study design, 93 lesions in the stomach, rectum, and colon from five European centers were treated with ESR. The median size of the lesions was 29 × 25 mm, and all lesions had a Paris Is/IIa morphology. The primary aim of the study was to assess the feasibility and safety of the ESR technique. Other standard parameters were evaluated as secondary outcomes, including the en bloc and R0 resection rates. The authors differentiated between lesions treated after circumferential incision with the FARIn U device (n = 70) and those treated without prior mucosal incision at the beginning of the study period (n = 23).

Overall, the feasibility of ESR was demonstrated in all procedures with a technical success rate of 100 %. One perforation, which was treated endoscopically with an over-the-scope clip, occurred. Two patients experienced postinterventional bleeding requiring endoscopic hemostasis. The en bloc and R0 resection rates for the first 23 lesions were both 8.7 %. However, these rates improved considerably in the second batch of lesions (n = 70) with prior circumferential incision; here, en bloc and R0 were 70 % and 63 %, respectively.

How do these results compare with other resection techniques? In a recent publication from our center, Nagl et al. demonstrated en bloc and R0 resection rates of 33.3 % and 32.1 %, and 18.4 % and 15.8 %, respectively, for UEMR and conventional EMR in colonic lesions between 20 mm and 40 mm in size [4]. The rate of severe adverse events was 0 %. The German ESD registry showed en bloc and R0 resection rates of 90 % and 80 %, respectively, for ESD in the rectum. For colonic ESD, the en bloc and R0 resection rates were 85 % and 72 %, respectively [5]. Even though the ESR procedures were mainly in the rectum (57/70; 61 %), it seems that ESR lies between UEMR and ESD in terms of en bloc and R0 resection rates. A possible role of ESR could be, for example, in the resection of colonic lesions larger than 30 mm and with signs of potential submucosal invasive cancer, where en bloc resection is desirable. In such cases, EMR and UEMR would be limited by their en bloc resection potential, while ESD expertise may not be available.

Metter et al. should be commended for producing multicenter data using a novel resection device in an interesting technique. Although the emphasis was laid on the primary outcomes of feasibility and safety, the secondary results also show impressive en bloc and R0 resection rates. The endoscopic community looks forward to seeing more data on the differentiation between ESR and hybrid ESD, which shares many similarities with ESR. In addition, the potential of higher quality specimens due to the deep cutting plane during ESR and its effects on histopathological analysis need to be addressed. Finally, the challenge of en bloc and R0 resection for expert endoscopists lies in the colon and less in the rectum or distal stomach, which is why prospective data on the performance of ESR, particularly in colonic lesions, would be of interest in the future.

Publication History

Article published online:
25 March 2022

• References

• 1 Nett A, Binmoeller K. Underwater endoscopic mucosal resection. Gastrointest Endosc Clin N Am 2019; 29: 659-673
• 2 Ebigbo A, Probst A, Römmele C. et al. Step-up training for colorectal and gastric ESD and the challenge of ESD training in the proximal colon: results from a German center. Endosc Int Open 2018; 6: E524-e30
• 3 Ferlitsch M, Moss A, Hassan C. et al. Colorectal polypectomy and endoscopic mucosal resection (EMR): European Society of Gastrointestinal Endoscopy (ESGE) Clinical Guideline. Endoscopy 2017; 49: 270-297
• 4 Nagl S, Ebigbo A, Goelder SK. et al. Underwater vs conventional endoscopic mucosal resection of large sessile or flat colorectal polyps: a prospective randomized controlled trial. Gastroenterology 2021; 161: 1460-74.e1
• 5 Fleischmann C, Probst A, Ebigbo A. et al. Endoscopic submucosal dissection in Europe: results of 1000 neoplastic lesions from the German Endoscopic Submucosal Dissection Registry. Gastroenterology 2021; 161: 1168-1178
• 6 Metter K, Aepli P, Dumoulin FL. et al. Endoscopic submucosal resection: a technique using novel devices for incision and resection of neoplastic lesions. Endoscopy 2022; 54: 1001-1006 DOI: 10.1055/a-1723-3194.