Transanal endoscopic microsurgery (TEM) for rectal GI stromal tumour.

[BACKGROUND] Rectal gastrointestinal stromal tumours (GIST) are uncommon and technically challenging to treat due to the confined pelvic anatomy and proximity to the anal sphincter complex. The oncological goal of surgery is R0 resection, but radical procedures often compromise function. Transanal endoscopic microsurgery (TEM/TEO) provides stable exposure and precise full-thickness excision, offering the possibility of organ preservation. The role of tumour size and neoadjuvant imatinib in enabling local excision remains under investigation.

[METHODS] We conducted a retrospective single-centre study of all consecutive patients undergoing TEM/TEO for rectal GIST between January 2007 and May 2023. Clinicopathological data, operative outcomes, postoperative course, and follow-up were analysed. Disease-free survival (DFS) and overall survival (OS) were estimated with the Kaplan-Meier method.

[RESULTS] Thirteen patients were included. Median age was 55 years (IQR 48-69), 69.2% were male, and median BMI was 26.1 kg/m (IQR 22.4-28.0). The median tumour distance from the anal verge was 6.0 cm (IQR 4.0-7.0), and the median pathological size was 5.0 cm (IQR 5.0-7.0). Two patients (15.4%) received neoadjuvant imatinib. Spinal anaesthesia was used in 69.2% of cases, with a median operative time of 80 min (IQR 60-110 min). Peritoneal opening occurred in one case (7.7%), which was repaired transanally. No conversions were required. Median hospital stay was 4 days (IQR 2-6), with no recorded postoperative complications; one patient (7.7%) required salvage reintervention. R0 resection was achieved in 92.3%. At a median follow-up of 60 months, two patients (15.4%) developed local recurrence and one patient (7.7%) died. The 12-month Kaplan-Meier estimates were 92.3% for DFS and 100.0% for OS.

[CONCLUSION] TEM/TEO achieved a high rate of R0 resection with organ preservation in this small single-centre series of rectal GIST. Tumour size alone should not be considered an absolute contraindication when en-bloc excision without rupture and negative margins are technically achievable. Neoadjuvant imatinib may facilitate local excision in selected borderline cases, but our experience is limited and larger multicentre registries are required to better define selection criteria and long-term outcomes.