Short-term outcomes of transanal completion total mesorectal excision (cTaTME) for rectal cancer: a case-matched analysis

Background: Local excision of early rectal tumors as a rectal preserving treatment is gaining popularity, especially since bowel cancer screening programs result in a shift towards the diagnosis of early stage rectal cancers. However, unfavorable histological features predicting high risk for recurrence within the "big biopsy" may mandate completion total mesorectal excision (cTME). Completion surgery is associated with higher morbidity, poorer specimen quality, and less favorable oncological outcomes compared to primary TME. Transanal approach potentially improves outcome of completion surgery for rectal cancer. The aim of this study was to compare radical completion surgery after local excision for rectal cancer by the transanal approach (cTaTME) with conventional abdominal approach (cTME).

Methods: All consecutive patients who underwent cTaTME for rectal cancer between 2012 and 2017 were case-matched with cTME patients, according to gender, tumor height, preoperative radiotherapy, and tumor stage. Surgical, pathological, and short-term postoperative outcomes were evaluated.

Results: In total, 25 patients underwent completion TaTME and were matched with 25 patients after cTME. Median time from local excision to completion surgery was 9 weeks in both groups. In the cTaTME and cTME groups, perforation of the rectum occurred in 4 and 28% of patients, respectively (p = 0.049), leading to poor specimen quality in these patients. Number of harvested lymph nodes was higher after cTaTME (median 15; range 7-47) than after cTME (median 10; range 0-17). No significant difference was found in end colostomy rate between the two groups. Major 30-day morbidity (Clavien-Dindo≥ III) was 20 and 32%, respectively (p = 0.321). Hospital stay was significantly longer after cTME.

Conclusion: TaTME after full-thickness excision is a promising technique with a significantly lower risk of perforation of the rectum and better specimen quality compared to conventional completion TME.