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

BACKGROUND: 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.

MATERIALS AND METHODS: 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.

RESULTS: 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 < 0.001) were observed. In addition, enhanced SDC1 protein expression correlated with negative estrogen receptor (ER) expression (OR, 2.38; 95% CI, 1.64-3.44; P < 0.001) and positive human epidermal growth factor receptor 2 (HER2) expression (OR, 1.77; 95% CI, 1.14-2.76; P = 0.01). However, increased SDC1 protein expression did not correlate with relapse-free survival (RFS) (HR = 0.33, 95% CI: 0.03-3.13; P = 0.33). There were no additional significant correlations observed between SDC1 protein expression and other clinical factors, including tumor size, lymph node involvement, nuclear grade, and progesterone receptor (PR) expression.

CONCLUSION: The results of this meta-analysis demonstrate that increased SDC1 protein expression in breast cancer is significantly associated with worse prognosis in terms of DFS and OS, and an aggressive phenotype is associated with negative ER expression and positive HER2 expression.