Comparison of Syndecan-1 Immunohistochemical Expression in Lobular and Ductal Breast Carcinoma with Nodal Metastases

Syndecan-1 (Sdc1) is a transmembrane heparan sulfate proteoglycan, an extracellular matrix receptor involved in intercellular communication, proliferation, angiogenesis, and metastasis. This study determined and compared Sdc1 expression in the tumor cells and stroma of 30 invasive lobular and 30 invasive ductal breast carcinomas (ILCs/IDCs), also in the axillary node metastases of ductal type, and correlated it with clinical and tumor parameters. Sdc1 was expressed in the epithelium of 90% carcinoma of both histological types. Also, it was most frequently expressed in their tumor stroma, but in ILC, stromal expression was negative in 40%. Sdc1 was expressed in 86.7% of the metastatic epithelium of IDC nodal metastases (in even 50% as high expression), while the nodal stroma was negative in 46.7%. Primary IDC showed a negative correlation between epithelial Sdc1 and progesterone receptors (PRs), whereas ILC showed a positive correlation between stromal Sdc1 and histological gradus. In the metastatic epithelium, Sdc1 was negatively correlated with a patient's age, estrogen receptors (ERs), and PRs in the primary tumors, while the stroma of metastases demonstrated a positive correlation with the focus number in primary tumors and a negative correlation with PRs in primary tumors. This research revealed identical overall epithelial Sdc1 expression in both breast carcinomas with no statistically significant difference in its stromal expression and confirmed the role of Sdc1 in the progression of both tumor types and in the development of ductal carcinoma's metastatic potential.