A comparative study of the pathological outcomes of robot-assisted versus open surgery for rectal cancer

Purpose: The use of robot-assisted surgery for rectal cancer is increasing, but the pathological outcomes have not been fully clarified. We compared the surgical and pathological outcomes between robot-assisted and open surgery in specimens from patients operated on for rectal cancer. Methods: All patients who underwent resection for rectal cancer from 2016 to 2018 were included (n = 137). Specimens were divided into 3 sections to analyze the pathology of the lymph nodes. Results: We compared the pathological outcomes between robot-assisted and open surgery in specimens from patients operated on for rectal cancer. The total specimen lengths were shorter in the robot-assisted group than in the open surgery group (mean +/- standard deviation: 29.1 +/- 8.6 cm vs. 33.8 +/- 9.9 cm, P = 0.004) because of a shorter proximal resection margin (21.7 +/- 8.7 cm vs. 26.4 +/- 10.6 cm, P = 0.006). The number of recruited lymph nodes (35.8 +/- 21.8 vs. 39.6 +/- 16.5, P = 0.604) and arterial vessel length (8.84 +/- 2.6 cm vs. 8.78 +/- 2.4 cm, P = 0.891) did not differ significantly between the 2 surgical approaches. Lymph node metastases were found in 33 of 137 samples (24.1%), but the numbers did not differ significantly between the procedures. Among these 33 cases, metastatic lymph nodes were located in the mesorectum (75.8%), in the sigmoid colon mesentery (33.3%), and at the arterial ligation site of the inferior mesenteric artery (12.1%). The circumferential resection margin and the proportion of complete mesorectal fascia were comparable between the groups. Conclusion: There were no significant differences between the 2 surgical approaches regarding arterial vessel length, recruitment of lymph node metastases, and resection margins.