Robotic-assisted surgery for mid and low rectal cancer: a long but safe learning curve

The number of robotic-assisted procedures for rectal cancer is rising. The risk of this procedure when performed by surgeon with limited robotic experience is unknown and the precise duration of the learning curve debated. We, therefore, aimed to analyze the learning curve and its related safety in a single center before the development of mentoring programs. We prospectively recorded all robotic procedures performed for colorectal cancer between 2015 and 2020 by a single surgeon. Operative times for partial and total proctectomy were analyzed. The learning curve was defined by comparison with the standard duration of the laparoscopic procedure performed in expert centers (published in GRECCAR 5 and GRECCAR 6 trials) and calculated using a cumulative summation for learning curve test (LC-CUSUM). Among the 174 patients operated for colorectal cancer, we analyzed the outcomes of the 89 patients operated by partial and total robotic proctectomy. To reach repeatedly the same surgical duration as laparoscopic procedure for partial or complete proctectomy, the LC-CUSUM identified a learning curve of 57 patients. A severe morbidity in this population, defined by Clavien-Dindo classification ≥ 3, was observed in 15 cases (16.8%) with an anastomotic leak rate of 13.5%. The rate of completeness of mesorectal excision was 90% and the mean number of harvested lymph nodes was 15 (± 9). Using operative time as end-point, the learning curve of rectal cancer robotic surgery identified a cut-off of 57 patients. The technic remained safe with acceptable morbidity and oncological outcomes.