A Comparison of Endoscopic Synchronous Injection and Submucosal Dissection(ESISD) and Conventional Endoscopic Submucosal Dissection(CESD) for Granular Mixed Nodular Laterally Spreading Tumor in the Rectum (LST-G-M)

Inclusion criteria

• Age ≥ 18 years.
• Endoscopic diagnosis of a large (≥ 20 mm) granular mixed nodular laterally spreading tumor (LST-G-M) located in the rectum.
• Lesion situated 0-15 cm from the anal verge.
• Pre-procedure imaging (e.g., EUS) and endoscopic assessment suggest a very low to low risk of lymph node metastasis (i.e., lesions confined to the mucosa or with superficial submucosal invasion < 1000 μm).
• Deemed suitable for Endoscopic Submucosal Dissection (ESD) based on a comprehensive clinical evaluation by the endoscopist.
• Provision of signed and dated informed consent form.

Exclusion criteria

• Coagulopathy that cannot be adequately corrected, including an international normalized ratio (INR) > 1.5 or a platelet count < 50,000/μL.
• Evidence of deep submucosal invasion (≥ 1000 μm) or obvious non-lifting sign, suggesting a need for surgical intervention.
• Pregnancy or lactation.
• Inability to tolerate deep sedation or general anesthesia.
• History of colorectal surgery (except for simple appendectomy or polypectomy).
• Presence of a synchronous colorectal cancer that requires priority treatment.
• Recurrent lesions at the same site.
• Any condition that, in the investigator's opinion, could increase the patient's risk or interfere with the study assessments.