Disparate E-cadherin mutations in LCIS and associated invasive breast carcinomas

Abstract

Aims - The relation between lobular carcinoma in situ (LCIS) and invasive breast cancer is unresolved. In an attempt to establish whether LCIS is a precursor of invasive cancer the mutational status and the expression of E-cadherin was analysed in LCIS and associated invasive breast carcinoma in 23 patients. Methods - Foci of LCIS and associated invasive carcinoma were individually microdissected from tissue from 23 patients. Exons 4-16 of the E-cadherin gene were analysed using single strand conformation polymorphism (SSCP); protein expression and the localisation of E-cadherin and β-catenin were assessed with the use of immunohistochemistry. Results - Immunohistochemistry revealed a lack of expression of E-cadherin and β-catenin in most LCIS samples and invasive foci. In all but four cases, the staining pattern was identical in the LCIS and associated invasive areas. When E-cadherin was absent, β-catenin was also undetected, suggesting a lack of expression of alternative classic cadherin members in these lesions. Coincident E-cadherin mutations in LCIS and associated invasive carcinoma were not identified in this series of patients. However, mutational analysis of E-cadherin in multiple foci of carcinoma in situ surrounding an invasive lesion provided evidence to support ductal carcinoma in situ as a precursor of invasive ductal carcinoma. Conclusion - These data support the hypothesis that LCIS is not a precursor of invasive breast carcinoma but a marker of increased risk of developing invasive disease.