Association of visceral adipose tissue with postoperative outcome in upper gastrointestinal cancer: a systematic review and meta-analysis

There is no consensus on the relation between visceral fat mass and long-term postoperative prognosis in patients with upper gastrointestinal (GI) cancer.The purpose of this study was to investigate the association of preoperative visceral fat mass with postoperative complications and overall survival (OS) in patients with upper GI cancer.We searched MEDLINE, the Cochrane Central Register of Controlled Trials, EMBASE (Dialog), the WHO International Clinical Trials Platform Search Portal, and ClinicalTrials.gov and identified observational studies published from inception through 20 July 2022. We conducted a systematic review and random-effects meta-analysis of studies including patients who were surgically treated for upper GI cancer and whose visceral fat mass was assessed on the basis of body composition. We independently assessed the risk of bias and quality of evidence using the Quality In Prognosis Studies and the Grading of Recommendations, Assessment, Development, and Evaluation approach, respectively. The primary outcome was OS. HRs and 95% CIs for OS were pooled.Ninety-one studies (n = 20,583) were included. All studies used computed tomography (CT) to assess the body composition of patients. Twenty-four studies reported the relation between high visceral fat and postoperative outcomes, and their results were synthesized. Compared with low visceral adipose tissue, high visceral adipose tissue assessed by CT may improve OS (HR: 0.69; 95% CI: 0.55, 0.87; I2 = 65%; n = 3407). The risk of bias for OS in each study was moderate or high. The certainty of evidence for OS was very low because of inconsistency in the forest plot, the moderate or high risk of bias, and publication bias.High visceral fat may be associated with improved OS after radical resection in patients with upper GI cancer. Further studies are needed to confirm these findings and mitigate the risk.