Open versus laparoscopic surgery for primary appendiceal tumors: a large multicenter retrospective propensity score-matched cohort study in Japan

Background The feasibility of laparoscopic surgery for primary appendiceal tumors compared to that of open surgery has not been demonstrated to date because primary appendiceal tumors are rare. This study aimed to compare the long-term outcomes between laparoscopic and open surgeries for primary appendiceal tumors. Methods In this multicenter retrospective cohort study, the data of patients who had been histologically diagnosed with primary appendiceal tumors at 43 tertiary hospitals in Japan between 2000 and 2017 were analyzed. In total, 922 patients were assessed, and 679 cases were eligible for analysis. Using propensity scores, the baseline characteristics were matched for 114 open surgery cases and 114 laparoscopic surgery cases. The primary endpoints were recurrence-free survival (excluding patients with stage IV disease with distant metastasis) and overall survival. Results The rate of conversion from laparoscopic to open surgery was 1.5%. The 5-year recurrence-free survival rates were 80.4% (95% confidence interval: 71.0-89.7) and 78.2% (95% confidence interval: 69.0-87.3) in the laparoscopic and open surgery groups, respectively, with no significant difference (p = 0.57). No significant difference was observed in the 5-year overall survival rates between the laparoscopic [83.5% (95% confidence interval: 74.4-92.7)] and open surgery [72.7% (95% confidence interval: 62.3-83.0);p = 0.09] groups. In multivariate analysis, laparoscopic surgery was not identified as an independent prognostic factor for overall survival [hazard ratio: 0.49 (95% confidence interval: 0.23-1.06),p = 0.0707]. Conclusions Laparoscopic surgery is comparable to open surgery and can be considered a treatment option for primary appendiceal tumors.