Outcomes of robotic low anterior resection versus transanal total mesorectal excision for rectal cancer

The quality of total mesorectal excision (TME) is regarded as a fundamental key to the oncological outcome of rectal cancer. Robotic low anterior resection (RLAR) and transanal TME (TaTME) were developed to overcome the technical challenges of conventional open TME. This study aimed to compare the short- and long-term outcomes of RLAR versus TaTME for rectal cancer.

Retrospective data from patients undergoing RLAR or TaTME at a colorectal unit in Singapore were analysed. The primary outcomes were the short-term clinical and pathological results including specimen margins and quality of TME. Secondary outcomes were recurrence, disease-free survival (DFS), and overall survival rates.

A total of 80 patients who underwent either RLAR or TaTME were analysed. The TaTME group had a shorter operating time than the RLAR group (354 versus 481 min respectively; P < 0.001) and fewer stays in the high-dependency and intensive care units (38.1 versus 73.7 per cent; P = 0.010). There was a higher rate of readmissions at 30 days in the TaTME group (19.0 versus 0 per cent; P = 0.006). Specimens from TaTME had greater proximal (14.0 versus 10.0 cm; P = 0.045) and distal (2.50 versus 1.65 cm; P = 0.021) margins. Patients undergoing TaTME had borderline longer DFS (25.9 versus 15.7 months; P = 0.049). Subgroup analysis of patients with (y)pT3-4 tumours showed fewer positive circumferential resection margins with TaTME (0 versus 18.2 per cent; P = 0.019) and improved DFS (25.9 versus 15.7 months; P = 0.017).

Superior margins were obtained with TaTME, especially in locally advanced tumours, although TaTME was associated with a higher readmission rate compared with RLAR.