Learning process analysis of robotic lateral pelvic lymph node dissection for local advanced rectal cancer: CUSUM-curve of 78 consecutive patients

Abstract

Abstract PurposeRobotic lateral lymph node dissection (LLND) has been suggested as a safe and feasible procedure for local advanced rectal cancer. However, no large case series has documented the learning curve for this technically demanding procedure.The aim of the present study was to evaluate the learning curve for robotic-assisted LLND for local advanced rectal cancer by a surgeon at a single institute.MethodsData on 78 consecutive patients who underwent robotic-LLND operation for rectal cancer were collected to evaluate surgical outcomes, postoperative urinary function changes and mid-term oncological outcomes. The learning curve was analyzed using the cumulative sum (CUSUM) method to assess changes in the unilateral LLND operative times across the case sequence.ResultsAmong the 78 patients, 52 patients underwent bilateral LLND and 28 patients underwent unilateral LLND. A total of 130 consecutive data were recorded. We arranged unilateral robotic-LLND operative times and calculated cumulative sum values, allowing differentiation of three phases: phase I (learning period), Cases 1–51; phase II (proficiency period), Cases 52–83; and phase III (mastery period), Cases 84–130. As the learning curve accumulated, the operation time and estimated blood loss of unilateral robotic-LLND decreased significantly with each phase (P＜0.05). At 12months after surgery, the International Prostatic Symptom Score of patients at phase III was significant lower than phase I (P＜0.05). No significant difference was observed in the overall survival, relapse-free survival and local recurrence among the three phases of the learning curve (P＞0.05).ConclusionThe CUSUM curve shows three phases in the learning and use of robotic-LLND which correspond to the phases of initial learning of the technique, proficiency and mastery. The data obtained suggest that the performance of robotic-LLND is safe in all of the three phases of the learning curve. And, the estimated learning curve for robotic assisted rectal-LLND is achieved after 51 cases.