Learning curve for single-port robot-assisted rectal cancer surgery

PURPOSE: We analyzed the learning curve of single-port robotic (SPR)-assisted rectal cancer surgery. METHODS: Fifty-seven consecutive SPR-assisted rectal cancer surgery cases performed by the same surgeon were considered in surgical interventions for rectal cancer. Total operation time (OT), docking time (DT), and surgeon console time (SCT) measured during surgery were used to parametrize the learning curve. The parameters representing the learning curve were evaluated using the cumulative sum (CUSUM). RESULTS: The mean value of total OT was 241.8 ± 91.7 minutes, the mean value of DT was 20.6 ± 19.1 minutes, and the mean value of SCT was 135.9 ± 66.7 minutes. The learning curve was divided into phase 1 (initial 16 cases), phase 2 (second 16 cases), and phase 3 (subsequent 25 cases). The peak on the CUSUM graph occurred in the 21st case. The longest OT among phases was in phase 2. Complications were most frequent in phase 2. However, complications of Clavien-Dindo (CD) grade IIIb were most frequent in phase 3 with 2 patients. The most common complications were fluid collection and urinary retention (7 patients each). Complications of CD grade IIIb required one stomal revision due to stoma obstruction and one irrigation and loop ileostomy due to anastomosis leakage. CONCLUSION: Improvement in surgical performance of SPR assisted rectal cancer operation was achieved after 21 cases. The three phases identified in the cumulative sum analysis showed a significant decrease in operative time after the middle stage of the learning curve without an increase in the complication rate.