Multicenter phase II trial of transanal total mesorectal excision for rectal cancer: preliminary results

Background Transanal TME (taTME) combines abdominal and transanal dissection to facilitate sphincter preservation in patients with low rectal tumors. Few phase II/III trials report long-term oncologic and functional results. We report early results from a North American prospective multicenter phase II trial of taTME (NCT03144765). Methods 100 patients with stage I–III rectal adenocarcinoma located ≤ 10 cm from the anal verge (AV) were enrolled across 11 centers. Primary and secondary endpoints were TME quality, pathologic outcomes, 30-day and 90-day outcomes, and stoma closure rate. Univariable regression analysis was performed to assess risk factors for incomplete TME and anastomotic complications. Results Between September 2017 and April 2022, 70 males and 30 females with median age of 58 (IQR 49–62) years and BMI 27.8 (IQR 23.9–31.8) kg/m 2 underwent 2-team taTME for tumors located a median 5.8 (IQR 4.5–7.0) cm from the AV. Neoadjuvant radiotherapy was completed in 69%. Intersphincteric resection was performed in 36% and all patients were diverted. Intraoperative complications occurred in 8% including 3 organ injuries, 2 abdominal and 1 transanal conversion. The 30-day and 90-day morbidity rates were 49% (Clavien–Dindo (CD) ≥ 3 in 28.6%) and 56% (CD ≥ 3 in 30.4% including 1 mortality), respectively. Anastomotic complications were reported in 18% including 10% diagnosed within 30 days. Higher anastomotic risk was noted among males ( p = 0.05). At a median follow-up of 5 (IQR 3.1–7.4) months, 98% of stomas were closed. TME grade was complete or near complete in 90%, with positive margins in 2 cases (3%). Risk factors for incomplete TME were ASA ≥ 3 ( p = 0.01), increased time between NRT and surgery ( p = 0.03), and higher operative blood loss ( p = 0.003). Conclusion When performed at expert centers, 2-team taTME in patients with low rectal tumors is safe with low conversion rates and high stoma closure rate. Mid-term results will further evaluate oncologic and functional outcomes. Graphical abstract