622. COMPARISON OF ROBOT-ASSISTED MINIMALLY INVASIVE ESOPHAGECTOMY WITH CONVENTIONAL MINIMALLY INVASIVE ESOPHAGECTOMY FOR ESOPHAGEAL CANCER: A MULTI-INSTITUTIONAL COHORT STUDY

Background The Japanese public insurance system approved robot-assisted minimally invasive esophagectomy (RAMIE) for esophageal cancer in 2018. Since then, an increasing number of RAMIE has been performed every year. However, it is unclear whether RAMIE is more beneficial than conventional minimally invasive esophagectomy (MIE) in terms of short-term and long-term outcomes. Methods A total of 396 patients (RAMIE, 145; MIE, 251) with resectable esophageal cancer who underwent esophagectomy between 2016 and 2019 at 6 institutions were included. A propensity score matching analysis was performed to compare the short-term outcome. Two-stage esophagectomy, salvage surgery, and palliative resection were excluded. Individual propensity scores were calculated based on the following 15 variables: age, sex, body mass index, American Society of Anesthesiologists Physical Status (ASA-PS), hemodialysis, oral steroid use, obstructive pulmonary disease, histology, tumor location, clinical T, N, M classification, preoperative therapy, field of lymphadenectomy, and organ used for reconstruction. Results After matching 272 patients were analyzed. RAMIE took the significantly longer operating time (629min; 570min, p=0.0005), but the amount of blood loss (90g; 84g), number of harvested mediastinal nodes (24; 25), and in-hospital mortality (1.5%; 0.7%) were comparable. RAMIE group showed a trend of less severe post-operative morbidity (Clavien–Dindo grade III or higher) (18%; 27%) and significant reduction of recurrent laryngeal nerve palsy (23%; 35%, p=0.046). The 5-year overall and relapse-free survival in the RAMIE and MIE groups were 65%; 61% [hazard ratio (HR), 0.77; 95% CI: 0.51, 1.17], and 61%; 51% (HR, 0.73; 95% CI: 0.51, 1.06), respectively. Conclusion RAMIE was safely performed even during the early period of its application. Despite the longer operating time, RAMIE would be a promising alternative to MIE, with a better trend of short- and long-term outcomes, including a significantly lower incidence of postoperative recurrent laryngeal nerve palsy.