Re-evaluation of possible vulnerable sites in the lateral pelvic cavity to local recurrence during robot-assisted total mesorectal excision

Background Despite mechanical and technical improvements in laparoscopic and robot-assisted (LAR) rectal cancer procedures, the absence of prognostic disparities among various approaches cannot improve the quality of TME. The present study re-evaluated robot-assisted total mesorectal excision (TME) procedures to determine whether these procedures may reveal technical faults that may increase the rate of local recurrence (LR). Methods This study enrolled 886 consecutive patients with rectal cancer, who underwent curative robot-assisted LAR at Asan Medical Center (Seoul, Korea) between July 2010 and August 2017 (the first vs second period;n = 399 vs 487). The quality of TME and lateral pelvic mesorectal excision (LPME) were analyzed, as were LR rates and survival outcomes. Results Complete TME and LPME were achieved in 89.2% and 80.1% of these patients, respectively, with <= 1% having incomplete TME excluding intramesorectal excision. LR rates were 13.5 and 14.5 times higher in patients with incomplete TME and LPME, respectively, than in patients with complete TME and LPME (14.8% vs 1.1% and 8.7% vs 0.6%;p < 0.001 each by univariate analyses). Multivariate analyses showed that defective LPME was independently associated with incomplete TME and vice versa (p < 0.001). Cox regression analysis showed that defective LPME was independently correlated with reduced 5-year disease-free survival rate (hazard ratio, 1.563; 95% confidence interval, 1.052-2.323;p = 0.027). Conclusions LR in rectal cancer patients was largely due to incomplete LPME, which was significantly associated with incomplete TME. Complete LPME may enhance the likelihood of complete TME, reducing LR rates.

Automated summary

Incomplete lateral pelvic mesorectal excision (LPME) in robot-assisted rectal cancer surgery is significantly associated with incomplete total mesorectal excision (TME) and higher rates of local recurrence (LR). Complete LPME may improve the likelihood of complete TME and lower LR rates.