Long-term outcome of patients with rectal cancer following transanal endoscopic microsurgery: real-world insights from a single-centre audit

• TEM outcomes depend on treatment intent, patient fitness and preferences • Preoperative imaging disagreed with pathology in 37% of patients • Three-quarters of patients achieve organ preservation and avoid local recurrence • Local recurrence risk is associated with tumour size and histologic features • Long-term continence problems seem more common after multimodal treatment Transanal endoscopic microsurgery (TEM) offers organ preservation to selected rectal cancer patients, but real-world outcomes need monitoring due to the evolving treatment landscape. In this observational, non-comparative study, we audited patients who underwent TEM (2015-2023), either upfront or following neoadjuvant therapy (NAT), assessing staging accuracy of endorectal ultrasound (ERUS) and magnetic resonance imaging (MRI), surgical and oncological results, and patient-reported outcomes (Wexner and EQ-5D-3L questionnaires at the end of the follow-up). Of 91 patients (adenocarcinoma, 87; neuroendocrine, 4; median 7 cm from the anal verge), 35 (38%) deviated from standard TEM indications, and 24 (26%) avoided completion total mesorectal excision (cTME) due to comorbidities or personal choice. Sixty-three (69%) with cT1-3N0 tumours underwent TEM, while 28 (31%) with cT1-3N0-1 tumours received NAT-TEM (mostly short-course radiotherapy). Positive margins were detected in 17.5% and 10.7%. All-grade complications were 7.7%. Imaging disagreed with pathology in 34 cases (37%), mainly due to overstaging; ERUS and MRI accuracy were 77% and 70% (TEM) and 44% and 58% (NAT-TEM). Following TEM, 16 (25%) patients underwent cTME, 1 (2%) redo-TEM, and 4 (6%) radiotherapy; following NAT-TEM, 3 (12%) patients underwent cTME. Organ preservation rate was 75% and 78%. At 62-month median follow-up, five-year local recurrence-free survival was 81%, consistent between groups and significantly associated with tumour size, lymphovascular and submucosal invasion. All patients with low-risk pT1N0 tumours remained disease-free. Long-term continence issues were more common after NAT-TEM. This real-world audit highlights deviations from standard TEM indications, discrepancies between radiological and pathological staging, and the need to monitor functional outcomes, particularly after multimodal treatment. Regardless, more than three-quarters maintained intestinal continuity and remain locally disease-free.