Clinicopathological Significance of CD44 and CD117 Expression/Co-Expression in Invasive Ductal Breast Cancer

Background/Objectives: Breast cancer (BC) is the most common cancer in women worldwide and has a high mortality rate; thus, it is essential to determine the relevance of not only standard clinicopathological parameters, but also non-standard parameters, such as cancer stem cell molecular markers CD44 and CD117. These factors could possibly be used to predict cancer aggressiveness and metastasis. The present study aimed to evaluate the significance of CD44 and CD117 expression/co-expression in relation to clinicopathological parameters, molecular cancer subtypes, and axillary lymph node (ALN) status in invasive ductal cancer (IDC) of the breast. Methods: The investigation included 136 patients with IDC in whom radical mastectomy had been performed. The level of CD44 and CD117 expression in cancer tissue (high or low) was determined via immunohistochemical analysis. Results: High CD117 expression and CD44/CD117 co-expression were closely linked to a higher Ki-67 index (p < 0.001; p = 0.003, respectively) and triple-negative breast cancer (TNBC) (p < 0.001; p < 0.001, respectively). Multivariate linear regression analysis revealed that CD44/CD117 co-expression was independently associated with a higher number (p < 0.001), as well as a higher percentage (p = 0.005) of metastatic ALNs. Conclusions: This study showed that CD44/CD117 co-expression is an independent predictor of a higher number and percentage of metastatic ALNs in IDC and may have potential prognostic value.