Relationships Between Immunophenotype, Ki-67 Index, Microvascular Density, Ep-CAM/P-cadherin, and MMP-2 Expression in Early-stage Invasive Ductal Breast Cancer

There is still a lack of complete consensus on immunohistochemical surrogate markers for luminal A (LA) and luminal B (LB), HER2, and basal-like subtypes of breast carcinomas and their correlation with cancer cell adhesion and invasion-promoting factors. Therefore, early-stage invasive ductal breast cancer patients (N = 209) were recruited to the study and divided into 4 subtypes, on the basis of the expression of the estrogen/progesterone receptor and HER2 (LA: 74.4% of cases; LB: 7.8%; HER2: 5.6%; and triple-negative phenotype: 12.2%). Regardless of the above-mentioned classification, we divided all carcinomas into 2 groups: carcinomas expressing at least 1 basal marker [cytokeratine (CK)5/6, CK5, vimentin, epidermal growth factor receptor, or aberrant CK8/18 expression-membranous or in < 10% of cells] versus carcinomas negative for basal markers. Then we studied the relationships between the above subtypes (2 classifications) and (i) the expression of adhesion molecules (Ep-CAM, P-cadherin), (ii) matrix metalloproteinases (MMP)-2, (iii) the proliferation index (MIB-1 LI), and (iv) the microvascular density. We confirmed that triple-negative phenotypes are characterized by basal marker expression, a high tumor grade, and high MIB-1 LI. In this subtype, we found MMP-2 expression in stromal leukocytes less frequently. Both LA carcinomas and carcinomas negative for basal markers were more often negative for epithelial cell adhesion molecule (Ep-CAM) and P-cadherin. Moreover, we noted a higher mean value of microvascular density in CK5/6 and Ep-CAM-immunopositive tumors, carcinomas with aberrant CK8/18 expression, and carcinomas with no or strong expression of MMP-2 in stromal fibroblast-like cells. These results might suggest that mechanisms of stroma remodeling and carcinogenesis (Ep-CAM is the suggested marker of breast progenitors) may differ between breast cancer subtypes.