479. TRANSTHORACIC VERSUS TRANSABDOMINAL SURGICAL APPROACH FOR SIEWERT TYPE II ESOPHAGOGASTRIC JUNCTIONAL ADENOCARCINOMAS—A PROPENSITY SCORE-MATCHED ANALYSIS

Abstract Background Esophagogastric junctional(EGJ) adenocarcinoma is a complex type of cancer that varies in etiology and disease pattern depending on the tumor level. There is increasing evidence on the need for different surgical approaches for different Siewert types. The optimal surgical approach for Siewert type II cancer remains controversial. This study aims to compare the oncological and surgical safety of transthoracic and transabdominal approaches for type II cancers. Methods The study included patients who underwent resection for Siewert type II adenocarcinomas from 2003–2020 in a single tertiary center using transthoracic (TT) and transabdominal (TA) approaches with macroscopic tumor clearance. The TT approach referred to Lewis-Tanner esophagogastrectomy, while the TA approach included total gastrectomy and proximal gastrectomy. Data from a prospectively-managed database were analyzed to compare postoperative morbidity and mortality rates, lymph node harvest, completeness of resection and overall survival between the two groups. Propensity score matching (PSM) was used in further analyses. Results Excluding R2 resections, there were 54 patients in the TT and 45 (proximal gastrectomy:23) in the TA groups. cT stages were comparable. In TT group, median tumor length was 6 cm (vs. 3 cm,p = 0.000), 18.5% with esophageal extension of >4 cm above EGJ;75.9% had nodal metastases (vs. 47.7%, p = 0.004);20.4% underwent neoadjuvant therapy (vs. 6.8%, p = 0.057). Anastomotic leak and cardiopulmonary complication rates, R0 resection rates, nodal yield and positive lymph node ratios were comparable. Proximal margin was involved in 15.9% for TA (vs. 5.6%, p = 0.092). Overall median survival times were similar (TT vs. TA: 42vs.65 months, p = 0.557). PSM yielded 33 patients per group. Only one in TT group had >4 cm esophageal involvement. Cardiac complication rate in TT group was 23.6%(vs. 3.5%, p = 0.024). Conclusion After correcting for selection bias, positive lymph node ratio, resection margin and overall survival did not differ for the TT and TA approaches. Resection by the TT approach is associated with more cardiac complications. For Siewert type II tumors with limited thoracic esophageal extension, the TA approach is safe and should be sufficient.