Prognostic and clinical significance of syndecan-1 expression in breast cancer: A systematic review and meta-analysis

The prognostic value of syndecan-1 (SDC1, also called CD138) in breast cancer remains controversial. Therefore, we performed a meta-analysis to assess the clinical significance of SDC1 expression in breast cancer. Various databases were searched to evaluate possible correlations between SDC1 protein or mRNA expression and prognostic significance in breast cancer. Pooled hazard ratios (HRs) and odds ratios (ORs) with 95% confidence intervals (CIs) were applied to perform a quantitative meta-analysis. A total of 1305 breast cancer patients from 9 eligible studies were included in this meta-analysis. Significant associations between elevated SDC1 protein expression and poor disease-free survival (DFS) (HR = 1.55, 95% CI: 1.12–2.14; P = 0.007) and overall survival (OS) (HR = 2.08, 95% CI: 1.61–2.69; P