Histopathological outcomes of transanal, robotic, open, and laparoscopic surgery for rectal cancer resection. A Bayesian network meta-analysis of randomized controlled trials

Background: While total mesorectal excision is the gold standard for rectal cancer, the optimal surgical approach to achieve adequate oncological outcomes remains controversial. This network meta-analysis aims to compare the histopathological outcomes of robotic (R-RR), transanal (Ta-RR), laparoscopic (L-RR), and open (O-RR) resections for rectal cancer. Materials and methods: MEDLINE, Embase, and the Cochrane Library were screened from inception to June 2024. Of the 4186 articles screened, 27 RCTs were selected. Pairwise comparisons and Bayesian network meta-analyses applying random effects models were performed. Results: The 27 RCTs included a total of 8696 patients. Bayesian pairwise meta-analysis revealed significantly lower odds of non-complete mesorectal excision with Ta-RR (Odds Ratio, OR, 0.60; 95%CI, 0.33, 0.92; P = .02; I2:11.7 %) and R-RR (OR, 0.68; 95%CI, 0.46, 0.94; P = .02; I2:41.7 %) compared with laparoscopy. Moreover, lower odds of positive CRMs were observed in the Ta-RR group than in the L-RR group (OR, 0.36; 95%CI, 0.13, 0.91; P = .02; I2:43.9 %). The R-RR was associated with more lymph nodes harvested compared with L-RR (Mean Difference, MD, 1.24; 95%CI, 0.10, 2.52; P = .03; I2:77.3 %). Conversely, Ta-RR was associated with a significantly lower number of lymph nodes harvested compared with all other approaches. SUCRA plots revealed that Ta-RR had the highest probability of being the best approach to achieve a complete mesorectal excision and negative CRM, followed by R-RR, which ranked the best in lymph nodes retrieved. Conclusion: When comparing the effectiveness of the available surgical approaches for rectal cancer resection, Ta-RR and R-RR are associated with better histopathological outcomes than L-RR.