263. LEARNING CURVE ANALYSIS USING CUMULATIVE SUM TECHNIQUES FOR ROBOT-ASSISTED MINIMALLY INVASIVE ESOPHAGECTOMY

Abstract Introduction Robot-assisted minimally invasive esophagectomy (RAMIE) has improved the technical difficulty of the conventional minimally invasive esophagectomy, by more precisely operated forceps and stability of the surgical fields. Although it is widely accepted that RAMIE demands excellence in robotic surgery, it is unclear how many cases were needed to reach the proficiency. This study aimed to investigate the learnings curve of two surgeons, with respect to perioperative findings. Methods Patients who underwent RAMIE using a Da Vinci Xi Surgical System between November 2018 and February 2024 were included. Surgeon A introduced RAMIE and Surgeon B started the training of RAMIE after standardization. Both surgeons were certified by the Japan Society for Endoscopic Surgery and qualified surgeon by the Japan Esophageal Society. A cumulative sum (CUSUM) analyses were performed for console time for thoracic procedure to generate the learning curves of each surgeon. The cases before the changepoint of the CUSUM curve was defined as phase I (learning phase), and after the changepoint as phase II (proficiency phase). The perioperative outcomes were compared between the phases. Results Surgeon A and B performed 63 and 33 cases, respectively. Surgeon B started RAMIE under guidance of Surgeon A, who had already experienced 39 cases at that time. CUSUM curve showed that Surgeon B required fewer cases to reach the phase II (proficiency phase) than Surgeon A (16 cases for Surgeon B vs. 27 cases for Surgeon A). There was no significant difference between the phase I and II in patient characteristics including age, sex, tumor location, neoadjuvant chemotherapy, and clinical TNM stages and the extent of lymph node dissection. Total operation time significantly decreased from phase I to phase II: 796 min [730-824] vs. 708 min [627-764]; P<0.01 for Surgeon A, 806 min [751-853] vs. 686 min [635-707]; P<0.01 for Surgeon B. During Phase I, console time of Surgeon B was significantly longer than console time of Surgeon A (408 min [354-432] vs. 360 min [325-385], P<0.01). However, in Phase II, the difference in time attenuated (281 min [255-299] vs. 266 min [244-316], P=0.68). There was no significant difference in intraoperative blood loss or the incidence of postoperative complications including recurrent laryngeal nerve palsy, anastomotic leakage and pneumonia. Conclusion It is suggested that training in standardized surgical procedures for RAMIE under the guidance of an experienced surgeon could accelerate the pace of learning.