Backgrounds and Objectives: Growing evidence indicates that metabolic syndrome confers a differential risk for the development and progression of many types of cancer, especially at digestive tract system. We therefore synthesized the results of published cohort studies to test whether baseline metabolic syndrome and its components can predict survival outcomes in patients with esophageal, gastric or colorectal cancer. Methods: Literature retrieval, publication selection and data extraction were performed independently and in duplicate. Data analyses were completed using STATA software, version 14.1. Results: In total, 15 publications involving 54656 patients were meta-analyzed. In overall analyses, the presence of metabolic syndrome was associated with a non-significant 19% increased mortality risk in digestive tract cancer (95% confidence interval [CI]: 0.95 to 1.49, P=0.130). In stratified analyses, the association between metabolic syndrome and digestive tract cancer was statistically significant in prospective studies (effect size [ES]: 1.64, 95% CI: 1.18 to 2.28), in studies involving postsurgical patients (ES: 1.42, 95% CI: 1.06 to 1.92), and in studies assessing cancer-specific survival (ES: 0.93, 95% CI: 0.81 to 1.06). Further meta-regression analyses indicated that age and smoking were potential sources of between-study heterogeneity (both P<0.001). The shape of the Begg's funnel plot seemed symmetrical (Begg's test P=0.945 and Egger's test P=0.305). Conclusions: Our meta-analytical findings indicate that metabolic syndrome was associated with an increased risk of postsurgical digestive tract cancer-specific mortality. Further validation and functional exploration are warranted. Funding Statement: This study was supported by the Joint Funds for the Innovation of Science and Technology of Fujian Province (Grant No. 2017Y9090 and 2017Y9082), the Natural Science Foundation of Fujian Province (Grant No. 2018Y0024), the Fundamental Research Funds for the Central Universities (Grant No. 3332018170), and the Ministry of Health P.R. China (WKJ2016-2-05). Declaration of Interests: The authors declare that they have no conflict of interest. Ethics Approval Statement: This meta-analysis was conducted according to the guidelines in the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement.