(2022) 22:812 Guo et al BMC Cancer https://doi.org/10.1186/s12885-022-09867-9 Open Access RESEARCH Prognostic value of CSN5 in patients with digestive system cancers: a systematic review and meta‑analysis Yonghua Guo1,2†, Meng Gao1,2†, Ye Yao1,2†, Jinghua Li1,2, Xi Chen1,2, Xingxing Wang1,2, Zhang Chen1,2, Yufeng Yuan1,2* and Weijie Ma1,2* Abstract Background: Despite the understanding of the COP9 signalosome subunit (CSN5) in tumor genesis, there is no conclusive evidence on its value to predict the survival and prognosis of digestive system tumor patients Hence this study aimed to evaluate the impact of CSN5 levels on the survival and clinicopathological parameters of digestive system neoplasm patients Methods: First, a comprehensive search was conducted in four databases We utilized the Hazard Ratio (HR) with a 95% confidence interval (CI) to evaluate the prognostic value of CSN5 for the overall survival (OS) and recurrence-free survival (RFS) of patients Then, we estimated the connection between CSN5 and the clinicopathological parameters based on the Odds Ratio (OR) with the corresponding 95% CI Results: This meta-analysis included 22 studies and 2193 patients diagnosed with digestive system tumors High expression of CSN5 was correlated to poorer OS (HR = 2.28, 95% CI: 1.71–3.03; p 7 Statistical analyses The inter-study heterogeneity was estimated by the χ2based Cochrane Q-test The definition of statistically significant heterogeneity was a χ2 p 50% If the inter-study heterogeneity was significant, a random-effect model was applied; otherwise, a fixedeffect model was performed HRs and their 95% Cis were utilized to evaluate the significance of CSN5 in the survival of digestive system cancer patients Lower CSN5 expression in patients with better survival was identified as HR > 1 In contrast, higher CSN5 expression in patients with a greater survival was recognized as HR