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

The goal of this clinical trial is to learn whether a new endoscopic device called the Speedboat works as well or better than the standard needle knife for removing large colonic nonpedunculated polyps. The study will also evaluate the safety of the Speedboat device. The main aims of the study are: * To compare the resection speed of colorectal endoscopic submucosal dissection (ESD) using the Speedboat device versus the standard needle knife. * To compare the en bloc resection rate and curative (R0) resection rate between the two techniques. * To evaluate the safety of using the Speedboat device compared with the needle knife in colorectal ESD. What will happen in this study Adults aged 18 years or older who have a large, flat colorectal polyp (greater than 20 mm) that cannot be safely removed with standard snare polypectomy may take part. Participants will be randomly assigned (like flipping a coin) to one of two groups: * Speedboat group: The lesion will be removed using the Speedboat device, which combines injection, cutting, and bleeding control in one tool. * Needle knife group: The lesion will be removed using the standard needle knife and other separate tools for injection and hemostasis. What participants will do Stay one night in the hospital before the colonoscopy for bowel preparation. Undergo colonoscopy and lesion removal under anesthesia. Have blood tests and monitoring for one day after the procedure. Be followed for two weeks to check for any complications. Have a follow-up colonoscopy 6-12 months later, depending on pathology results. Where and how the study will be done The study will take place at five hospitals in Thailand: Faculty of Medicine Siriraj Hospital, Mahidol University King Chulalongkorn Memorial Hospital Rajavithi Hospital National Cancer Institute of Thailand Phra Nakhon Si Ayutthaya Hospital About 80 participants will join the study. All procedures will be performed by experienced endoscopists who have performed at least 5