Prognostic significance of RSPO1, WNT1, P16, WT1, and SDC1 expressions in invasive ductal carcinoma of the breast

Background: To better understand the mechanisms of the SDC1 expression in invasive ductal carcinoma, we studied the correlations between SDC1 expression and related gene expressions (RSPO1, WNT1, WT1, and P16). Methods: Using 100 cases of invasive ductal carcinoma tissue, we screened expressions of RSPO1, WNT1, WT1, P16, and SDC1 using immunohistochemistry. We analyzed the association between the immunoreactivities and clinicopathological parameters. Results: WT1 expression was associated with tumor grade. RSPO1 expression was associated with progesterone receptor expression. Expressions of RSPO1, WT1, and P16 were significantly associated with disease-free survival. RSPO1 and P16 showed statistically significant hazard ratios. SDC1 ectodomain expression was significantly associated only with P16 expression. Immunoreactivity of SDC1 cytoplasmic domain was associated with WT1 and WNT1. However, WNT1 expression failed to show a significant association with disease-free survival. Conclusions: RSPO1 and P16 immunoreactivity was found to be an independent prognostic indicator in invasive ductal cancer. Cytoplasmic expression of SDC1 is positively correlated with tumor-prone proteins (WT1 and WNT1) and membranous expression of SDC1 is positively correlated with the tumor suppressor (P16).