Cumulative sum analysis of the learning curve of laparoendoscopic single-site robot-assisted radical prostatectomy

Background: Radical prostatectomy has become the gold standard for treating localized prostate cancer. Improvement in the single-site technique and surgeon's skill reduces not only the hospital duration but also the number of wounds. Realizing the learning curve for a new procedure can prevent unnecessary mistakes. Objective: To analyze the learning curve of extraperitoneal laparoendoscopic single-site robot-assisted radical prostatectomy (LESS-RaRP). Methods: We retrospectively evaluated 160 patients diagnosed with prostate cancer during June 2016 to December 2020 who underwent extraperitoneal LESS-RaRP. Calculated cumulative sum analysis (CUSUM) was used to evaluate the learning curves for the extraperitoneal setting time, robotic console time, total operation time, and blood loss. The operative and functional outcomes were also assessed. Results: The learning curve of the total operation time was observed in 79 cases. For the extraperitoneal setting and robotic console times, the learning curve was observed in 87 and 76 cases, respectively. The learning curve for blood loss was observed in 36 cases. No in-hospital mortality or respiratory failure was observed. Conclusion: Extraperitoneal LESS-RaRP using the da Vinci Si system is safe and feasible. Approximately 80 patients are required to achieve a stable and consistent operative time. A learning curve for blood loss was observed after 36 cases.