417. POSTOPERATIVE CHYLE LEAK - LESS LIKELY IN OBESE PATIENTS AND ASSOCIATED WITH POSTOPERATIVE MORTALITY

Abstract Background Esophagectomy can be complicated by postoperative chyle leak (PCL). PCL is a rare condition but accounts for considerable morbidity and can be challenging to manage. Predisposing factors and the impact of PCL on survival are not fully understood. This study aimed to investigate risk factors for PCL in a national cohort and its associations, if any, with outcomes and survival. Methods All patients with esophageal cancer in the Swedish Registry for Esophageal and Gastric Cancer (NREV) who underwent esophagectomy between 2006 and 2018 with information on complications were included in this study. Risk factors and protective factors of PCL were explored with multivariable logistic regression and 90-day mortality was described. Adjusted and overall survival was studied with Cox-regression and the Kaplan-Meier method. Results The study included 1540 patients that underwent esophageal resection. 51 patients (3.3%) had PCL of which 32 (62.7%) were managed operatively. Median time in hospital increased with 14 days from 15 to 29 days in patients with PCL compared to patients without. In multivariable logistic regression, overweight (BMI>25) and obese (BMI>30) patients were significantly less likely to suffer from postoperative chyle leak, OR 0.41 (0.19-0.88 95%CI) and OR 0.28 (0.08-0.97) respectively. In patients with PCL, 90-day mortality was increased three-fold, 15.7% vs 5.0%, and median survival was six months shorter (28.8 vs 34.8 months) compared to patients without PCL. Despite this, PCL was not significantly associated with poor overall survival in multivariable adjusted analysis, HR 1.12 (0.75-1.66 95%CI). Conclusion Postoperative chyle leak remains a serious complication following esophagectomy. This study finds a reduced risk of PCL in obese patients by unknown mechanisms that should be further explored. Even though short-term mortality is clearly affected by PCL this complication does not seem to impact long-term survival.