Elevated Syndecan-1 levels in the sera of patients with breast cancer correlate with tumor size

Breast cancer is the leading type of cancer in Iranian women and affects them at least one decade younger than their counterparts in developed countries. Breast tumor progression and metastasis is accompanied by a decrease in the membranous expression of Syndecan-1 and an increase in its shedding. We measured the level of soluble Syndecan-1 in the sera of Iranian patients with breast cancer. The study population included 61 chemotherapy-naive breast cancer patients and 30 age/sex-matched healthy individuals. Blood was collected by venipuncture method and serum was separated, aliquoted and kept at −40 °C until used. A commercial ELISA was used to detect Syndecan-1 levels in the sera. Soluble Syndecan-1 levels were increased in the sera of patients with breast cancer compared to healthy controls (87.89 ± 89.29 vs. 47.57 ± 46.46 ng/ml, p = 0.005). There was a positive correlation between soluble Syndecan-1 levels and tumor size (p = 0.017). The serum level of Syndecan-1 in patients without calcification showed a trend of increase compared to that of patients with calcification (108.80 ± 101.76 vs. 59.82 ± 57.13 ng/ml). The positive correlation between soluble Syndecan-1 levels and tumor size in the present study highlights the importance of different varieties (cell-bound and soluble) of this molecule in the breast tumor progression and their significance as tumor biomarkers.