261. CONVERSION ESOPHAGECTOMY FOR CT4B ESOPHAGEAL CANCER - MIE VS OPEN -

Background and Aims The standard treatment for locally advanced unresectable esophageal cancer is definitive chemoradiotherapy (dCRT), however, after induction chemotherapy with a triplet chemotherapy regimen (docetaxel, cisplatin, and 5-FU: DCF) or dCRT, conversion surgery could be performed if esophageal cancer is considered resectable. Furthermore, minimally invasive surgery such as robot-assisted or thoracoscopic procedures are expected to improve the outcome of patients with advanced esophageal cancer. We investigated the feasibility of minimally invasive esophagectomy (MIE) in conversion surgery. Materials and Methods Sixty-six patients who underwent conversion thoracic esophagectomy for cT4b esophageal cancer from 2007 to 2023 were included. The short-term outcomes of 25 open esophagectomy group and 41 MIE group (8 robot-assisted and 33 thoracoscopic) were compared. Results No differences in age, gender, PS, tumor location, histology, cN, or cM were observed between the two groups. cT4b organs tended to be in the airway in the MIE group (airway 70.7% vs 44%, major vessels 19.5% vs 24%, both 9.7% vs 32%, p=0.04) and DCF therapy was significantly performed in the MIE group for induction therapy (DCF 87.8% vs 56%, dCRT 12.2% vs 44%, p<0.001). On the other hand, salvage surgery was significantly associated with open esophagectomy (24.3% vs. 52%, p=0.003). There was no difference in surgical outcomes regarding thoracic operation time (157 min vs. 180 min, p=0.09), whereas the total operation time was significantly shorter in the MIE group (392 min vs. 439 min, p=0.02). Blood loss was significantly lower in the MIE group (79 ml vs. 470 ml, p<0.001), and R0 resection rate did not differ (82.9% vs. 72%, p=0.357). There were no significant differences in postoperative complications including pneumonia (26.8% vs. 44%, p=0.183) and recurrent nerve palsy (21.9% vs. 36%, p=0.260), but anastomotic leakage was significantly lower in the MIE group (4.8% vs. 24%, p=0.04). There was no difference in median postoperative hospital stay (16 [11-20] vs. 16 [14-29] days), however, median ICU stay (3 [3-4] vs. 4 [3-4] days, p=0.03) and readmission within 1 month after discharge (2.4% vs. 16%, p=0.04) were significantly lower in the MIE group. In-hospital mortality was observed in 1 case in the MIE group and 3 in the open esophagectomy group. Conclusion Despite the bias associated with the transition of treatment modalities and surgical techniques, MIE may contribute to improved short-term outcomes in conversion surgery.