Learning curve of Da Vinci robot-assisted radical gastrectomy for gastric cancer

Abstract

Objective To investigate the learning curve of Da Vinci robot-assisted laparoscopic radical gastrectomy for gastric cancer. Methods The retrospective cohort study was conducted. The clinicopathological data of 42 patients who underwent Da Vinci robot-assisted radical gastrectomy for gastric cancer in the First Affiliated Hospital of Xi′an Jiaotong University from October 2017 to August 2018 were collected. There were 30 males and 12 females, aged from 36 to 84 years, with an average age of 59 years. The learning curve was evaluated using the cumulative sum (CUSUM) analysis and the best fitting curve method. According to the minimum number of surgeries required to cross the learning curve, the patients were divided into learning stage group and mastery stage group. Then general data and surgical efficacy of the two groups were compared. Observation indicators: (1) surgical situations; (2) results of CUSUM analysis; (3) comparison of general data between the two groups; (4) comparison of surgical efficacy between the two groups; (5) follow-up. Patients were followed up by outpatient examination or telephone interview to detect the postoperative complications, tumor recurrence and metastasis up to February 2019. Measurement data with normal distribution were presented as Mean±SD, and comparison between groups was done using the independent sample t test. Count data were represented as absolute number, and comparison between groups was analyzed using the chi-square test or Fisher exact propability. Comparison of ordinal data between groups was analyzed using the Mann-Whitney U test. Results (1) Surgical situations: all the 42 patients underwent Da Vinci robot-assisted radical gastrectomy for gastric cancer successfully, without conversion to open surgery or perioperative death. Fourteen out of 42 patients underwent Da Vinci robot-assisted total radical gastrectomy and 28 underwent Da Vinci robot-assisted distal radical gastrectomy. The operation time and docking time were (213±31)minutes and (26±11)minutes. The operation time and docking time had a tendency to decreasing as the surgical cases increasing. (2) Results of CUSUM analysis. The CUSUM learning curve were best modeled as a polynomial with equation: CUSUM (operation time)=0.016 9X3-1.913 3X2+ 50.985X-16.595, CUSUM(docking time)=0.012 8X3-1.070 7X2+ 22.189X-23.097 respectively (X means the surgical case). The P value of fitting test of models was 0.05). There was no significant difference in the previous abdominal surgery history between the two groups (P>0.05). (4) Comparison of surgical efficacy between the two groups: operation time, volume of intraoperative blood loss, number of lymph nodes harvested, time to first liquid food intake, cases with postoperative complications and duration of postoperative hospital stay were (230±25)minutes, (176±103)mL, 21±7, (5.1±2.0)days, 2, (9.3±2.5)days in the learning stage group, and (191±18)minutes, (95±41)mL, 21±6, (4.7±1.7)days, 3, (8.4±2.1)days in the mastery stage group, respectively. There were statistically significant differences in the operation time and volume of intraoperative blood loss between the two groups (t=5.951, -3.359, P 0.05). There was no significant difference in the cases with postoperative complications between the two groups (P>0.05). (5) Follow-up: all the 42 patients were followed up for 6-16 months, with a median time of 11 months. No serious long-term complications, tumor recurrence and metastasis or death occurred during the follow-up. Conclusions The CUSUM learning curve of Da Vinci robot-assisted radical gastrectomy for gastric cancer can be divided into the learning stage and the mastery stage. It is suggested that the surgeons need to finish 19 cases or more to master Da Vinci robot-assisted radical gastrectomy for gastric cancer. Key words: Gastric neoplasms; Gastric cancer; Cumulative sum analysis; Best fitting curve; Learning curve; Da Vinci robotic surgical system