Prognostic value of syndecan-1 expression in breast cancer

Syndecan-1 is a cell surface heparan sulphate proteoglycan which participates in cell proliferation, cell migration and cell-matrix interactions. Epithelial syndecan-1 expression is reduced in several malignant tumours, but in breast and pancreatic cancer, increased expression has also been described. Loss of epithelial syndecan-1 has been associated with poor prognosis in some forms of cancer, but previous findings in breast cancer have been contradictory. The objective of this study was to evaluate the prognostic value of the immunohistochemical expression of syndecan-1 in a series of 200 patients with invasive breast cancer with a median follow-up of 17 years.

Formalin-fixed paraffin-embedded specimens were stained using a monoclonal antibody against syndecan-1.

Syndecan-1 was expressed in the epithelium in 61% and in the stroma in 67% of the tumours. Epithelial syndecan-1 expression was associated with negative oestrogen receptor (ER) status (p < 0.01), and stromal syndecan-1 expression with positive ER status (p = 0.02). The breast cancer-specific 10-year overall survival for patients with epithelial syndecan-1 expression was 65%, compared with 82% for those with loss of epithelial expression (p = 0.02). Ten-year survival was 66% for those expressing stromal syndecan-1 and 83% for those lacking stromal expression (p = 0.15). Patients with both epithelial and stromal expression had a 10-year survival of only 56%, compared to 78% in patients with other expression pattern combinations (p < 0.002). In Cox multivariate analysis, only axillary involvement and tumour size were significant predictors of breast cancer-specific survival.

Concomitant expression of syndecan-1 in both epithelium and stroma may be a predictor of unfavourable prognosis in breast cancer, and in contrast with previous studies, loss of epithelial syndecan-1 was associated with a more favourable prognosis.