Comparison of Efficacy and Safety of Speedboat Device and Needle Knife for Colorectal Endoscopic Submucosal Dissection: a Multicenter Randomized Study

1. Background/Rationale Colonoscopy screening and polypectomy have led to earlier identification and removal of precancerous lesions, which significantly decrease colorectal cancer incidence and mortality.(1, 2) While most polyps can be resected with snare polypectomy, up to 15% of them are not suitable for conventional colonoscopic removal due to a variety of reasons such as large size, difficult location, or previous resection attempts.(3) The guidelines' recommendation is to remove colorectal lesions < 10 mm with cold snare polypectomy and consider endoscopic mucosal resection (EMR) for lesions sized 10 to 19 mm. For the treatment of nonpedunculated large-sized lesions (> 20mm), both EMR and endoscopic submucosal dissection (ESD) can be used. However, achieving en bloc resection with EMR can be difficult, and piecemeal resections are associated with reduced histopathological assessment quality and higher local recurrence rates. Thus, for lesions larger than 20 mm, ESD is recommended.(4, 5) From an oncological standpoint, colorectal polyp with high suspicion for deep submucosal invasion (invasion depth more than 1,000 μm), and the morphology presented of severely disrupted vascular structures, surgery should be the treatment of choice. While the lesion presented a high suspicion of limited submucosal invasion (invasion depth less than 1,000 μm), ESD should be preferred as the risk of lymph node metastasis was low. (3) Given the thin wall colon and narrow/angulated colonic lumen, colorectal ESD is considered a challenging procedure and carries a high risk of complications. A bunch of devices, accessories, and techniques were created to overcome this difficulty as well as to shorten the procedural time and reduce the risk of perforation. (Table1) The conventional steps of colorectal ESD include submucosal injection, mucosal incision, submucosal dissection, and hemostasis. These steps are switched back and forth with the use of an injection needle, cutting and dissecting knife, and coagulation forceps. To shorten the step of device exchange, the cutting knife with an injectable channel was developed, ie. Dual knife (Olympus, Tokyo, Japan), Flush knife (Fujifilm, Tokyo, Japan), Hybrid knife (ERBE, Tubingen, Germany). (Table 1) These knives are monopolar electrosurgical devices that require higher voltages with associated risk of complications.

Recently, a newly designed electrosurgical knife incorporating an injection needle and cutting knife with hemostasis, namely Speedboat (Creo Medical Ltd, UK), has been created. The Speedboat blade delivers bipolar radio frequency (RF-400KHz) cutting and microwave coagulation (5.8GHz) for hemostasis and contains a retractable needle for submucosal injection/tissue irrigation. It also has an insulated hull to prevent thermal injury to the underlying muscle layer. Figure 1 Preliminary data suggest the safety and utility of this device in performing a variety of endoscopic dissection and resection procedures, including endoscopic submucosal dissection, peroral endoscopic myotomy, and resection of subepithelial tumors.

For colorectal ESD, the initial report has been announced by the group from St Mark's Hospital.(6) The treatment outcome in terms of en bloc resection, muscularis propria injury, and recurrence rate was comparable to those reported from the use of conventional knives. However, it has been shown that monopolar coagulation forceps for hemostasis were required in only 12.5% of cases. This might help to reduce the overall cost of accessory use. The exchange of accessories was also minimized with the use of the Speedboat device in many procedures(7), which might reduce the total procedural time. There is also growing published data regarding the feasibility and safety of using Speedboat devices in colorectal ESD. Figure 2 Although this all-in-one device proposed several advantages, there are some limitations that might mitigate the generalizability. It requires a dedicated electrosurgical generator along with a Speedboat device, which incurs additional costs. Moreover, close coordination between the endoscopist and the assistant maneuvering the device for optimum orientation of the dissection plane is required. Thus, it is worth comparing the effectiveness and safety of colorectal ESD using a Speedboat device with the conventional techniques using separate devices in a prospective, randomized, controlled trial.

Objectives Primary objective - To investigate the resection speed of colorectal endoscopic submucosal dissection using the Speedboat device compared with the standard needle knife.

Secondary objectives

• To investigate the en bloc resection rate and curative resection(R0) rate between using a Speedboat and needle knife in colorectal ESD.
• To investigate the safety of using a Speedboat and needle knife in colorectal ESD.