Noninferiority multicenter prospective randomized controlled study of rectal cancer T2–T3s (superficial) N0, M0 (T2T3sN0M0) undergoing neoadjuvant treatment and local excision (TEM) versus total mesorectal excision (TME): Preoperative, surgical, and pathological outcomes—The TAUTEM-study.

3501 Background: The standard surgical treatment of rectal adenocarcinoma above T1 is total mesorectal excision (TME), but it is associated with high morbidity and quality of life disorders. Transanal endoscopic microsurgery (TEM) achieves minimal postoperative morbidity rates. The treatment of T2, T3 superficial, N0, M0 rectal cancers is TME due to local excision achieving high recurrence rates. Initial reports of preoperative chemoradiotherapy (CRT) in association with TEM shows reduction in local recurrence. The TAU-TEM study aims to demonstrate the non-inferiority of the oncological outcomes and the improvement in morbidity and quality of life achieved with CRT-TEM compared with TME. Methods: Prospective, multicenter, randomized controlled non-inferiority trial including patients with rectal adenocarcinoma less than 10 cm from the anal verge and up to 4 cm in size, staged as T2T3sN0M0. Patients were randomized to: CRT-TEM (Arm A) or TME (Arm B). Postoperative morbidity and mortality were recorded and patients in both arms completed quality of life questionnaires when starting treatment and 6 months after surgery. Patients attended follow-up controls for local and systemic relapse. Trial registration: ClinicalTrials.gov Identifier: NCT01308190. Results: From July/2010 to October/2021, 173 patients from 17 Spanish hospitals were included (Arm A: 86, Arm B: 87). Ten were excluded after randomization (Arm A: 4, [3 re-staged > T2T3sN0M0, 1 refused follow-up study]; Arm B: 6 [4 refused the arm, 2 re-staged > T2T3sN0M0]). Therefore, the patients with modified intention to treat analysis were: TME, 81 and CRT-TEM, 82. There was no mortality after CRT. In this group, 2 patients abandoned neoadjuvant therapy; thus 80/82 (97.6%) completed CRT. The CRT-morbidity was low (25/82, 30%) and of low grade (95% G1-2). In the CRT-TEM group, MRI showed disease progression in 3 patients who were treated with TME. Finally, 77 patients underwent TEM surgery. One patient died in each arm (1.2%). Postoperative morbidity was 41/81 (50.6%) (Arm B) and 17/82 (20.7%) (Arm A) (p < 0.001, 95 CI% 43.9 to 15.9). Median Comprehensive Complication Index was 8.7 (IQR 20.9) Arm B and 0 (IQR 0) Arm A (p < 0.001). Median hospital stay was 7 days (IQR 7) Arm B and 2 days (IQR 2) Arm A (p < 0.001). Complete response in Arm A was 45.3% (34/75 patients) with 5.3% ypT3 (4/75 patients) and in Arm B: pT1 (12.3%; 10/81patients), deep-pT3 (4.95; 4/81patients), pN1 (21%; 17/81). Conclusions: CRT-TEM treatment obtains high pathological complete response rates (45.3%), with a high CRT compliance rate (97.6%) and low morbidity. Postoperative complications and hospitalization are significantly lower in the CRT-TEM group. We await the results of the follow-up. Clinical trial information: NCT01308190.