Long-term Results of the North American Phase II Transanal Total Mesorectal Excision Multicenter Trial for Rectal Cancer

BACKGROUND: Transanal total mesorectal excision (taTME) facilitates sphincter preservation in low rectal cancer. Preliminary results and functional outcomes from the North American multicenter phase II taTME trial (NCT03144765) have been published. Three-year outcomes are reported. METHODS: Patients with stage I to III rectal adenocarcinoma were enrolled across 11 centers (2017-2022). Endpoints included TME grade, 3-year overall survival, disease-free survival, cancer-specific survival, recurrence, late (beyond 90 d) complications, and stoma-free survival. Surveillance followed National Comprehensive Cancer Network guidelines, with pelvic magnetic resonance imaging (MRI) at 3 years to assess for pelvic sidewall recurrence when possible. Kaplan-Meier analysis assessed oncologic outcomes. RESULTS: One hundred patients underwent taTME for tumors at a median of 5.8 cm from the anal verge, with intersphincteric resection in 36% and handsewn anastomosis in 54%. Median follow-up was 50.9 months. Late complications occurred in 32 patients, including 21 severe (Clavien-Dindo ≥3). Late anastomotic complications occurred in 5 patients; one required surgical revision. Estimated 3-year overall survival, cancer-specific survival, and disease-free survival were 93.7%, 96.6%, and 84.6%, respectively. Distant recurrence occurred in 15 patients (median: 17.6 months), most commonly in the lung and liver. Locoregional recurrence occurred in 2 patients. Preoperative N stage, lymph node yield, tumor deposits, and perineural invasion were associated with recurrence. Among 100 patients diverted at taTME, 97% were stoma-free at 3 years; 4 patients later underwent secondary diversion. CONCLUSIONS: Three-year outcomes of this multicenter trial support the safety and efficacy of taTME in resectable mid and low rectal tumors, with outcomes comparable to contemporary studies. Longer-term oncologic and functional outcomes are needed.