Transanal down-to-up dissection of the distal rectum as a viable approach to achieve total mesorectal excision in laparoscopic sphincter-preserving surgery for rectal cancer near the anus: a study of short- and long-term outcomes of 123 consecutive patients from a single Japanese institution.

Background: In rectal cancer (RC) surgery, the complexity of total mesorectal excision (TME) in laparoscopic sphincter-preserving surgery (lap-SPS) for RC near the anus has been a critical issue. Recently, technical assistance via the anus for complete TME has been receiving attention. This study aimed at clarifying the transanal down-to-up dissection viability for achieving TME in lap-SPS for RC near the anus.

Methods: We evaluated surgical and oncological outcomes of a total of 123 consecutive patients undergoing either a transanal rectal dissection (TARD) under direct vision mobilizing the most difficult portion of TME via the anus or the transanal TME by using an endoscopic system (TaTME) for achieving TME in lap-SPS for RC near the anus between January 2006 and February 2021.

Results: A total of 123 consecutive patients (83 men) with a median age of 66 years (range 33-86 years) were included. TARD and TaTME were performed for 50 (40.7%) and for 73 (59.3%) patients, respectively. Preoperative treatment was performed for 40 (32.5%) patients, resulting in a complete pathological response in 5 (12.5%) patients. Intersphincteric resection was performed significantly more in the TARD group (p<0.001). Although the TaTME group needed a longer operative time at the transanal portion (p<0.001), the median blood loss was lower (p<0.001). Postoperative complications with the Clavien-Dindo classification grade ≧2 developed in 52 (42.3%) patients. Urinary dysfunction and stoma-related complications were found most frequently. More patients needing medication for urinary dysfunction were found in the TARD group, but a significant difference was not observed (10.0% vs. 6.8%, p=0.526). The quality of TME was good for almost all patients. Recurrence developed in 18 (14.6%) patients. The 5-year overall survival (OS) and relapse-free survival (RFS) rates in 123 patients were 95.8% and 88.8%, respectively. The 5-year OS and RFS between the two groups were comparable.

Conclusions: Our data suggested that a transanal down-to-up dissection of the distal rectum might be a viable approach in lap-SPS for RC near the anus. Further studies are needed to examine the differences between TARD and TaTME.