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Evolving techniques and technologies in colorectal endoscopic submucosal dissection: changing treatment paradigms and takeaways from a recent randomized trial

      Abbreviations:

      ESD (endoscopic submucosal dissection), LST-NG (nongranular laterally spreading tumor)
      Endoscopic submucosal dissection (ESD) is a well-established but technically demanding technique for treating a variety of lesions throughout the GI tract. Multiple guidelines from Japan, Europe, and the United States recommend ESD as a preferred strategy for superficial colorectal lesions according to morphologic and endoscopic criteria (ie, depressed morphology, advanced surface pattern, and nongranular lateral spreading tumor [LST-NG]), especially for lesions ≥20 mm.
      • Pimentel-Nunes P.
      • Pioche M.
      • Albeniz E.
      • et al.
      Curriculum for endoscopic submucosal dissection training in Europe: European Society of Gastrointestinal Endoscopy (ESGE) position statement.
      • Tanaka S.
      • Kashida H.
      • Saito Y.
      • et al.
      JGES guidelines for colorectal endoscopic submucosal dissection/endoscopic mucosal resection.
      • Draganov P.V.
      • Wang A.Y.
      • Othman M.O.
      • et al.
      AGA Institute clinical practice update: endoscopic submucosal dissection in the United States.
      ESD is advantageous over traditional piecemeal EMR, given its ability to allow for en bloc resection of any type of superficial lesion regardless of size and low rate of recurrence.

      McCarty TR, Aihara H. Current state of education and training for endoscopic submucosal dissection: translating strategy and success to the United States. Dig Endosc. Epub 2019 Dec 3.

      This ability for en bloc resection achieved by ESD allows adequate orientation of the pathologic specimen and a reliable staging for submucosal invasion, preventing unnecessary surgery for lesions at low risk for lymph node metastasis.
      In the performance of conventional ESD, the perimeter of the lesion is first marked with cautery, followed by injection of a lifting agent into the submucosa. Then, the mucosa is partially incised with an electrosurgical knife. Once the submucosa is exposed, freehand dissection is performed concurrently with alternating partial mucosal incisions until complete resection is achieved.
      • Maple J.T.
      • Abu Dayyeh B.K.
      • et al.
      ASGE Technology Committee
      Endoscopic submucosal dissection.
      Given the challenging nature of the procedure, the past few decades have seen a paradigm shift in the evolution of technologies and techniques. Various types of assistive devices, including traction devices, injectable ESD knives, and the use of a balloon overtube for endoscope stability, have been designed to improve procedure performance and resection outcomes and to reduce the risk of adverse events. The pocket-creation method was first reported in 2014 by Hayashi et al
      • Hayashi Y.
      • Sunada K.
      • Takahashi H.
      • et al.
      Pocket-creation method of endoscopic submucosal dissection to achieve en bloc resection of giant colorectal subpedunculated neoplastic lesions.
      as a technique developed to facilitate colorectal ESD.
      In this issue of Gastrointestinal Endoscopy, Yamashina et al
      • Yamashina T.
      • Nemoto D.
      • Hayashi Y.
      • et al.
      Prospective randomized trial comparing the pocket-creation method and conventional method of colorectal endoscopic submucosal dissection.
      designed a prospective randomized trial comparing the pocket-creation method with the conventional method of colorectal ESD. The pocket-creation method uses a tunneling technique to create a submucosal pocket beneath the lesion to facilitate submucosal dissection. This technique is designed to improve endoscope stability during ESD and to prevent dissipation of injected solution by minimizing the length of the initial mucosal incision. In the previous retrospective single-center study, the pocket-creation method was shown to significantly improve en bloc and R0 resection rates and to enhance dissection speed in comparison with the conventional ESD technique.
      • Takezawa T.
      • Hayashi Y.
      • Shinozaki S.
      • et al.
      The pocket-creation method facilitates colonic endoscopic submucosal dissection (with video).
      This prospective multicenter study included 118 patients with colorectal lesions randomized in a 1:1 fashion to undergo ESD by a pocket-creation method versus conventional ESD with the primary outcome of procedure completion, defined as completion of ESD within 3 hours with en bloc resection without a change to other methods. The lesions were located throughout the colon, extending from the cecum to the rectum; the median lesion size was 30 mm in both groups. In this study, the authors demonstrated that the rate of ESD completion was significantly higher in the pocket-creation method cohort than in the conventional ESD group (93.22% vs 72.72%; P = .01). Despite these findings, en bloc (94.92% vs 94.55%; P = 1.00) and R0 (86.44% vs 87.27%; P = 1.00) resection rates were not different between the 2 groups, nor was procedure time (51 vs 49 minutes; P = .33) or dissection speed (15.9 vs 17.4 mm2/min; P = .81).
      The results of this study provide an important early experience with the pocket-creation method in comparison with conventional ESD. The specific strengths of this study include its prospective multicenter randomized design, the inclusion of both experienced and trainee endoscopists, and the large number of patients enrolled based on a sample size calculation. Most importantly, this is the first randomized trial to compare the pocket-creation method with a conventional approach.
      Although this trial possesses several strengths, its results should also be interpreted with some caution. The inclusion of nonexpert endoscopists in this study, some with no conventional ESD experience (ie, experience with only the pocket-creation method), may have affected the rate of procedure completion on an intention-to-treat analysis. This in turn may have inflated the outcomes of pocket ESD while underestimating the true performance of conventional ESD. Familiarity with newer techniques or devices is important, given the learning curve or clinical expertise needed to perform an effective procedure, especially because the authors have commented that conventional ESD is a sophisticated and technically demanding procedure. Additionally, the per-protocol analysis is difficult to interpret because this methodology discounts the randomization process and no longer ensures comparability of the 2 groups (ie, the 2 groups may no longer be considered as balanced for known and unknown confounders).
      As mentioned previously, several methods and technologies are available to assist or improve the conventional ESD technique. Two of the proven methods include the pocket-creation method and the use of a traction device. Previous reports have shown that the use of a traction device results in significantly reduced procedure time and technical difficulty. In a prospective randomized trial of traction-assisted ESD versus conventional ESD, Ritsuno et al
      • Ritsuno H.
      • Sakamoto N.
      • Osada T.
      • et al.
      Prospective clinical trial of traction device-assisted endoscopic submucosal dissection of large superficial colorectal tumors using the S-O clip.
      found that the mean procedure time for the clip-assisted ESD group was significantly shorter (37.4 ± 32.6 vs 67.1 ± 44.1 min; P = .03). Another retrospective study by Jacques et al
      • Jacques J.
      • Charissoux A.
      • Bordillon P.
      • et al.
      High proficiency of colonic endoscopic submucosal dissection in Europe thanks to countertraction strategy using a double clip and rubber band.
      demonstrated that traction using a double clip and rubber-band technique significantly decreased procedure time (94.7 vs 117 min; P = .004) and increased procedure speed (28.2 vs 16.7 mm2/min; P < .0001), en bloc resection rate (95.7 % vs 76.3 %; P < .0001), and R0 resection rate (78.5 % vs 64.5 %, P =  .04) in comparison with conventional ESD.
      • Jacques J.
      • Charissoux A.
      • Bordillon P.
      • et al.
      High proficiency of colonic endoscopic submucosal dissection in Europe thanks to countertraction strategy using a double clip and rubber band.
      Given the current landscape of conventional ESD in Asia and the West, both experienced and novice endoscopists are likely to encounter changing treatment paradigms and continued evolution of ESD techniques. Despite multiple GI guidelines listing ESD as a preferred strategy for superficial colorectal lesions, it bears mentioning that no specific organization provides current guidance on technique or technology to achieve resection. Although the pocket-creation method and traction-assisted methods have been increasingly adopted to facilitate ESD, no current study directly compares these 2 methods. As such, a future study comparing the pocket-creation method with traction-assist methods for colorectal ESD is needed.
      In summary, ESD remains a challenging, though highly effective, minimally invasive treatment for superficial colorectal lesions. The ability of ESD to achieve complete en bloc resection of these lesions, and thus prevention of unnecessary surgery, will no doubt continue to inspire gastroenterologists to design new strategies with the aim of reducing the current complexity of the procedure. Future well-designed randomized studies using experienced endoscopists and novice trainees are needed to adequately assess the various ESD methods and techniques, to identify appropriate learning curves in training and mastery, and to determine which strategies may best translate into meaningful changes in clinical practice.

      Disclosure

      Hiroyuki Aihara is a consultant for Olympus America, Boston Scientific, Fujifilm Medical Systems, Medtronic, Auris Health, and Lumendi. The other author disclosed no financial relationships.

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