This is a prospective randomized controlled trial that aimed to compare the short-term clinical outcomes, functional outcomes, costs, and recurrence rates between endoscopic submucosal dissection (ESD) and transanal minimally invasive surgery (TAMIS) for early rectal neoplasms.

Background: Transanal minimally invasive surgery (TAMIS) is an effective surgical alternative to transanal excision for treating early rectal neoplasms not amenable to en bloc resection by conventional colonoscopic techniques. Endoscopic submucosal dissection (ESD) is a revolutionary endoscopic procedure that enables en bloc resection of large rectal neoplasms with low morbidity. To date, no randomized controlled trial can be found in the literature comparing the two modalities.

Objectives: To compare the short-term clinical outcomes, functional outcomes, costs, and recurrence rates between ESD and TAMIS for early rectal neoplasms.

Design: Prospective randomized controlled trial.

Subjects: One hundred and fourteen consecutive patients diagnosed with early rectal neoplasms (>/=2 cm in size and without evidence of deep submucosal invasion) that are not amenable to en bloc resection by conventional colonoscopic techniques will be recruited.

Interventions: Patients will be randomly allocated to receive either ESD or TAMIS.

Outcome measures: Primary outcome: 30-day morbidity/mortality defined by the Clavien-Dindo classification. Secondary outcomes: hospital stay, functional outcomes and quality of life, overall costs, R0 resection rate, and recurrence rate.

Conclusions: Results of the present study can provide evidence-based clarification of the efficacy and safety of ESD in treating early rectal neoplasms. The Investigators hypothesize that ESD is associated with lower morbidity, shorter hospital stay, and similar R0 resection rate when compared with TAMIS. A faster recovery and earlier discharge after ESD may reduce financial burden to the hospital/healthcare system. The results of this proposed project may have a significant impact on the future treatment strategy for early rectal neoplasms.

Inclusion Criteria:

• Patients diagnosed with nonpedunculated early rectal neoplasms >/= 2 cm in size in the rectum (>/= 3 cm and </= 18 cm from the anal verge) that are deemed not feasible for en bloc resection with conventional polypectomy or EMR as judged by two experienced endoscopist
• Age of patients >18 years;
• American Society of Anesthesiologists (ASA) grading I-III
• Informed consent available

Exclusion Criteria:

• Presence of endoscopic signs of massive submucosal invasion (including excavated/depressed morphology, Kudo's pit pattern Type V, or Sano's capillary pattern Type IIIB)
• Evidence of deep invasion on endorectal ultrasonography
• Unfavorable histopathologic features on biopsy (mucinous cancer, poor differentiation, or gross submucosal invasion)
• Patients with other synchronous colorectal neoplasms in addition to the index neoplasm that are indicated for surgical resection
• Patients with recurrence from previous Endoscopic Mucosal Resection or ESD
• Patients with known metastatic disease
• Patients with non-correctable coagulopathy