Reduction of E-cadherin expression is associated with non-lobular breast carcinomas of basal-like and triple negative phenotype

Aim: E-cadherin inactivation in breast cancer has been shown to be strongly associated with lobular breast cancer. However, little is known about the levels of E-cadherin expression according to the breast cancer molecular'' subtypes. The aim of this study was to address the distribution of E-cadherin expression according to the different molecular subtypes of breast cancer. Methods: E-cadherin expression was immunohistochemically analysed in a tissue microarray containing duplicate cores of 245 invasive breast carcinomas, of which 182 cases were of non-lobular histology, using a semi-quantitative scoring system based on the percentage of cells showing membrane immunopositivity. Results: In non-lobular breast carcinomas, reduced and/or negative E-cadherin expression was significantly associated with lack of oestrogen receptor expression, low levels of CCND1 expression, positivity for cytokeratins 5/6 and 17, epidermal growth factor receptor and caveolins 1 and 2, p53 expression, high MIB-1 proliferation indices, basal-like phenotype and triple negative phenotype. Conclusion: This study demonstrates that in the group of non-lobular breast cancers, reduction/lack of E-cadherin expression is preferentially found in basal-like breast carcinomas.