Effect of transanal vs. laparoscopic total mesorectal excision on 5-year overall survival in patients with rectal cancer: The TaLaR trial.

3631 Background: Transanal total mesorectal excision (taTME) has emerged as a widely adopted surgical approach for rectal cancer. Prior studies have reported favorable short-term outcomes, histopathological quality, and complication profiles for taTME compared with laparoscopic total mesorectal excision (laTME). However, the long-term oncologic effectiveness of taTME remains debated. In our previous work, we demonstrated that 3-year disease-free survival after taTME was noninferior to that after laTME among patients with mid-to-low rectal cancer. Building on these findings, the present study aimed to report the 5-year overall survival (OS) between taTME and laTME. Methods: We conducted a phase 3, randomized, open-label, noninferiority trial to compare the survival outcomes of taTME versus laTME in patients with rectal cancer located below the peritoneal reflection. This trial encompassed 16 hospitals across 10 provinces in China, with a total enrollment of 1,115 patients. We set the 3-year disease-free survival (DFS) and 5-year overall survival (OS) as the primary endpoints for analysis. This analysis of the 5-year overall survival was conducted following a predefined modified intention-to-treat principle. This study is registered with ClinicalTrials.gov, number NCT02966483. Results: As of June 2025, the overall 5-year overall survival (OS) rate was 83.60%, comprising 86.06% in the transanal TME (taTME) group and 81.24% in the laparoscopic TME (laTME) group. The overall 5-year disease-free survival (DFS) rate was 75.90%, with DFS rates of 77.65% in the taTME group and 74.18% in the laTME group. Conclusions: Based on preliminary results from a five-year follow-up, taTME is expected to achieve a five-year overall survival (OS) that is non-inferior to laTME. Our findings will support the routine use of taTME in mid-to-low rectal cancer, particularly in men, obese individuals, and those who have received neoadjuvant therapy. Clinical trial information: NCT02966483 . 5-year survival results between the laTME group and the taTME group. laTME taTME HR 5-year OS（97.5% CI） 81.24% (77.82%-84.82%) 86.06%(83.04%-89.20%) 0.73 (0.54-1.10) 5-year DFS（95% CI） 74.18%(70.45%-78.10%) 77.65%(74.15%-81.32%) 0.86(0.68-1.11)