Transanal Versus Laparoscopic Total Mesorectal Excision for Rectal Cancer

Background:In recent years, transanal mesorectal excision (TaTME) has emerged as a promising surgical alternative for rectal cancer, especially for mid and low rectal cancer. Theoretically, TaTME holds the potential advantage of providing better access to mobilize the distal rectum, and thus could achieve better pathologic outcomes, such as lower involved circumferential margin (CRM) and incomplete resected mesorectum, which could translate into better oncological outcome for the patients in the long term. However, until now, the feasibility and the non-inferiority (compared with laparoscopic total mesorectal excision, LpTME) of this technique has only been validated in studies with limitations of small sample size, retrospective nature. Study Objective:This study aims to evaluate the TaTME technique compared with conventional laparoscopic rectal surgery, focusing on resection quality, as well as long-term survival results. Study design This study is a prospective, multi-center, randomized, open-label, parallel group trial. The randomisation ratio of TaTME over LpTME will be 1:1. A central electronic data capture (EDC) system will be utilized for randomization, electronic CRF and data collection. All comparative analyses will be conducted on an "intention to treat" basis. Sample size: Sample-size calculation of this trial based on 3-year DFS and 5-year OS; but the sample size according to 5-year OS was larger than that based on 3-year DFS. The expected 5-year OS among clinical stage I-III rectal cancer patients treated with laTME was 77·4%. Allowing a difference of 10% as the non-inferiority margin, 910 patients would be required to sufficiently declare taTME noninferior to laTME in 5-year OS based on a log-rank test with an α error of 2·5% (in a two-sided test) and power of 80%. Assuming a dropout rate of 20%, a total of 1114 patients were planned to enroll for this trial. Study Endpoints:The primary end point of this study is 3-year disease-free survival (DFS) rate and a 5-year overall survival (OS) rate. Secondary endpoints include: 1) resection quality, mainly including circumferential involvement rate, and completeness of mesorectum. Resected specimen was pathologically processed and assessed at each center by trained and qualified pathologists independently.2)short term operative results such as morbidity and mortality, etc.; 3) long term oncological outcome such as local recurrence, and overall survival. Besides, functional outcome and quality of life are also evaluated.