Oncologic safety of transanal total mesorectal excision after neoadjuvant chemoradiotherapy for advanced rectal cancer: long-term outcomes compared with robot TME.

BACKGROUND

Transanal total mesorectal excision (taTME) was introduced to improve distal dissection in low rectal cancer, but some previous studies have concerns about increased local recurrence during taTME. This study compared the long-term oncologic outcomes of taTME and robotic TME (R-TME) in neoadjuvant chemoradiotherapy (nCRT)-treated advanced rectal cancer.

METHODS

We analyzed patients with advanced rectal cancer who received nCRT followed by minimally invasive TME using either taTME or robotic TME between 2008 and 2018. These patients were classified according to surgical approach: taTME and R-TME. The 5-year disease-free survival (DFS), local recurrence-free survival (LRFS), and distant recurrence-free survival (DRFS) were primary end point. Subgroup analyses were performed by yp stage, yT stage and tumor height (AV < 5 vs ≥ 5 cm). Additional propensity score matching was performed to reduce treatment selection bias.

RESULTS

A total of 306 patients were included, of whom 94 underwent taTME and 212 underwent R-TME between 2008 and 2018. There were no significant differences in OS, DFS, LRFS, or DRFS between two groups. After 1:1 propensity score matching, 88 matched pairs were generated, and matched analyses also showed no statistically significant association between surgical approach and OS, DFS, LRFS, or DRFS. In subgroup analyses stratified by yp stage, yT stage, and by unfavorable factors (male, BMI ≥ 25 kg/m2, and undergoing nCRT), long-term oncologic outcomes showed similar between taTME and R-TME. Among patients with ultra-low rectal cancer (AV < 5 cm), 5-year OS, DFS, and LRFS did not differ between two groups.

CONCLUSION

In nCRT-treated advanced mid and low rectal cancer, taTME showed no statistically significant difference in long-term oncologic outcomes compared with R-TME, and no statistically significant increase in local recurrence was observed, including in ultra-low rectal cancer (AV< 5 cm). These findings suggest that taTME may be considered a reasonable surgical option in selected patients.