Comparative efficacy and safety of injection mucosa knife versus conventional techniques in endoscopic submucosal dissection for rectal laterally spreading tumors

Endoscopic submucosal dissection (ESD) is a standard treatment for rectal laterally spreading tumors (LSTs). This study aims to compare the efficacy and safety of the Injection Mucosa Knife (IMK) technique versus the conventional Dual Knife (DK) technique in ESD for rectal LSTs. A total of 229 patients with rectal LSTs were enrolled from four hospitals between June 2020 and June 2025 and were divided into two groups: the IMK group (n = 108) and the DK group (n = 121). The primary outcome measures included total procedure time, mucosal dissection time, and submucosal dissection rate, while the secondary outcomes encompassed intraoperative and postoperative complications as well as the R0 resection rate. Additionally, the efficacy and safety of the two groups were compared based on tumor size and endoscopic morphology. The IMK group demonstrated significantly shorter total procedure time (median 50 vs. 65 min, P < 0.001) and mucosal dissection time (median 40 vs. 56 min, P < 0.001), along with a higher submucosal dissection rate (median 0.12 vs. 0.08 cm²/min, P < 0.001). There were no significant differences in intraoperative perforation, severe hemorrhage, R0 resection, postoperative bleeding, fever, or pathology between the two groups (P > 0.05). Subgroup analyses based on tumor size (2.5 cm and ≥ 2.5 cm) and morphology (LST-G and LST-NG) consistently showed superior efficiency of the IMK technique without compromising safety. The IMK technique significantly improves the efficiency of ESD for rectal LSTs by reducing operative time and enhancing dissection rates, while maintaining comparable safety and outcomes to the conventional DK technique. IMK represents a promising advancement in ESD for rectal lesions.