Transanal versus robotic total mesorectal excision for mid- and low-rectal cancer: A single-center comparative cohort of 109 patients

Minimally invasive total mesorectal excision (TME) for rectal cancer can be performed via transanal TME (TaTME) or robotic TME (R-TME), yet comparative evidence in predominantly non-obese Asian cohorts remains limited. We evaluated a consecutive retrospective cohort during our institutional transition from TaTME to R-TME. Between 2016 and 2022, 109 patients with mid- or low-rectal adenocarcinoma underwent curative TaTME (n = 40) or R-TME (n = 69). The primary analysis used propensity score matching (37 pairs) based on age, sex, and tumor location. Outcomes included pathologic margins and lymph-node yield, perioperative results, and 3-year progression-free survival (PFS) and overall survival (OS). In the matched cohort, pathologic outcomes were comparable, with similar circumferential resection margin/distal margin positivity and lymph-node yield; distal margin length showed a nonsignificant trend toward being longer after TaTME (median 1.8 vs. 1.5 cm; P = 0.079). R-TME required longer operative time (median 330 vs. 251 min; P < 0.001) but was associated with less blood loss (30 vs. 90 mL; P = 0.014) and shorter hospital stay (7 vs. 8 days; P = 0.016); conversion occurred in 13.5% after TaTME versus 0% after R-TME (P = 0.054). Three-year OS and PFS did not differ between groups (log-rank P = 0.701 and P = 0.898, respectively), and results were consistent in a sensitivity analysis restricted to 2019–2020. Limitations include retrospective design, modest sample size, and temporal confounding. In this transition cohort, TaTME and R-TME achieved comparable short-term oncologic and survival outcomes; R-TME offered perioperative advantages, while TaTME showed a trend toward a longer distal margin that warrants cautious interpretation.