Learning curve of multiple surgeons for robot-assisted radical prostatectomy using the cumulative sum method: a retrospective single-institution study

Prostate cancer (PC) is common among men and has become a significant societal issue. Localized PC has a good prognosis with appropriate treatment. Prostatectomy, particularly robot-assisted radical prostatectomy (RARP), has become a common treatment since the da Vinci prostatectomy was approved by the FDA in 2001. The current study aimed to assess the learning curve for RARP, focusing on anastomosis time, using the cumulative sum (CUSUM) method. Data were collected from Nagoya City University Hospital between May 2011 and December 2018 and included 469 surgeries performed by experienced surgeons. Our findings indicated that, on average, 11 patients were required to complete the initial phase and 24 patients were required to complete the consolidation phase of anastomosis. Additionally, for complete resection of pT2c cases, 16 cases were required for the initial phase and 27 cases were required for the consolidation phase. The CUSUM method proved useful for visualizing trends in surgical proficiency, although the study noted potential confounding biases and limitations in evaluating surgical proficiency based solely on surgical time or positive surgical margins.