Background: Accumulating studies have demonstrated YKL-40 associated with the prognosis of several cancers and contributed to the tumor progression through promoting tumor angiogenesis, migration, invasion and metastasis. The objective of this meta-analysis was to investigatethe relationship between YKL-40 and prognosis inpatients with solid tumors and seek for a new prognostic biomarker.Method: Relevant studies were searched in the Medline (PubMed), Web of science, and Embase. Pooled HR of

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... e. Pooled HR of overall survival and disease-free survival (DFS) were calculated to evaluate the strengthof the association between YKL-40 and cancer prognosis by using Stata software 14.0.Results: In total, 30 studies comprising 5160 patients were considered eligible and enrolled into the final meta-analysis. According to the meta-analysis results, higher expression of YKL-40 predicted poorer OS (pooled HR=1.85 CI%=1.58-2.18;P<0.001) and DFS (pooled HR =3.63 95% CI =2.63-5.01; P<0.001).Conclusion: The current evidence suggests that YKL-40 has a predictive effect onsurvival of cancer patients as indexed by DFS and OS. YKL-40 tissue expression is a valuable prognostic biomarker and may be a promising therapeutic target for solid tumors.