Prognostic value of endoglin-assessed microvessel density in cancer patients: a systematic review and meta-analysis

Endoglin (ENG, CD105), an auxiliary receptor for several TGF-β superfamily ligands, is constitutively expressed in tumor microvessels. The prognostic value of ENG-assessed microvessel density (MVD) has not been systemically analyzed. This meta-analysis reviews and evaluates the association between ENG expression and prognosis in cancer patients. Thirty published studies involving in 3613 patients were included after searching of PubMed, Web of Science, and EMBASE. The pooled hazard ratios (HRs) and 95% confidence intervals (CIs) for overall survival (OS), disease-free survival (DFS), and cancer-specific survival (CSS) were calculated using random-effects models. The publication bias was detected by a Begg's test and Egger's test. The outcome stability was verified by sensitivity analysis. The high ENG-assessed MVD was significantly associated with poor OS (HR = 2.14, 95% CI 1.62-2.81; < 0.001), DFS (HR = 3.23, 95% CI 2.10-4.95; < 0.001), CSS (HR = 3.33, 95% CI 1.32-8.37; < 0.001). Furthermore, subgroup analysis revealed that the association between the overexpression of ENG in tumor microvessels and the outcome endpoints (OS or DFS) were also significant in the Asians and Caucasians patients with different cancer types. ENG of tumor microvessels is a predictor of poor OS, DFS and CSS and may be a prognostic marker of patients with cancer.