Identification of a Subtype of Poorly Differentiated Invasive Ductal Carcinoma of the Breast Based on Vimentin and E-cadherin Expression

Abstract Objective The use of molecular markers can identify a subgroup of tumors with distinct recurrence patterns. The present study aimed to characterize the immunohistochemical expression of vimentin (VIM), of E-cadherin (CDH1), and of cytokeratin 5 (CK5) in patients with invasive ductal carcinomas (IDCs). Methods We have constructed a tissuemicroarray (TMA) from87 patients with IDC of the breast. Immunohistochemistry (IHC) was performed to study the expression of estrogen and progesterone receptors (ER and PgR), human epidermal growth factor receptor 2 (HER2), VIM, CDH1, CK5, and Ki67. The tumors were classified as luminal A and B (n = 39), HER2 enriched (n = 25), and triple-negative (TNBC) (n = 23), based on the IHC expression. Results We have observed that luminal A and B tumors lack the VIM+/CDH1-/low phenotype. This phenotype was observed in 16.5% of the HER2+ tumors and in 60% of the TNBC tumors (p = 0.0001). Out of a total of 20 TNBC tumors, the CK5 (basal-like marker) was positive in 11 of them. The VIM+/CDH1-/low phenotype was observed in 5 CK5+ TNBC tumors (45%) and in 7 out of 9 CK5- TNBC tumors (78%) (p = 0.02). The median Ki67 index in the VIM+/CDH1-/low tumors was 13.6 (range: 17.8-45.4) compared with 9.8 (range: 4.1-38.1) in other tumors (p = 0.0007). The presence of lymph nodemetastasis was less frequent in patients with VIM+/CDH1-/low tumors (23% versus 61%; X2 test; p = 0.01). Conclusion Our findings suggest that the expression of VIM and CDH1 can identify a subset of IDCs of the breast with a mesenchymal phenotype associated with poor prognosis, high-grade lesion, and high mitotic index.