Comparison of the operative outcomes and learning curves between laparoscopic and "Micro Hand S" robot-assisted total mesorectal excision for rectal cancer: a retrospective study.

The Micro Hand S robot is a new surgical tool that has been applied to total mesorectal excision (TME) surgery for rectal cancer in our center. In this study, we compared the operative outcomes, functional outcomes and learning curves of the Micro Hand S robot-assisted TME (RTME) with laparoscopic TME (LTME). A total of 40 patients who underwent RTME and 65 who underwent LTME performed by a single surgeon between July 2015 and November 2018 were included in this retrospective study. Clinicopathologic characteristics, operative and functional outcomes, and learning curves were compared between the two groups. The learning curve was analyzed using the cumulative sum method and two stages (Phase 1, Phase 2) were identified and analyzed. All patients were followed up for at least 12 months. The clinicopathologic characteristics of the two groups were similar. The learning curve was 17 cases for RTME and 34 cases for LTME. Compared with LTME, RTME was associated with less blood loss (148.2 vs. 195.0 ml, p = 0.022), and shorter length of hospital stay (9.5 vs. 12.2 days, p = 0.017), even during the learning period. With the accumulation of experience, the operative time decreased significantly from Phase 1 to Phase 2 (RTME, 360.6 vs. 323.5 min, p = 0.009; LTME, 338.1 vs. 301.9 min, p = 0.005), whereas other outcomes did not differ significantly. Micro Hand S robot-assisted TME is safe and feasible even during the learning period, with outcomes comparable to laparoscopic surgery but superior in terms of blood loss, length of hospital stay, and learning curve. Trial registration Clinicaltrial.gov, NCT04836741, retrospectively registered on 5 April 2021.