Expression patterns of β-catenin in in situ and invasive breast cancer

Background. β-Catenin plays a central role in the E-cadherin/catenin cell-cell adhesion complex and is possibly involved in cellular signalling pathways. In this study, we evaluated the expression patterns of this molecule in in situ and invasive breast cancer. Methods. The expression of β-catenin was evaluated in 121 breast cancer specimens by immunohistochemistry. Its relationship to clinicopathological features was also investigated. Results. Altered β-catenin expression was found in 68% of tumours. Lobular carcinomas showed abnormal β-catenin expression more frequently (77%) than ductal carcinomas (64%) with 46% of lobular cases showing complete absence of β-catenin immunoreactivity. Cytoplasmic β-catenin localization was seen only in ductal carcinomas. Aberrant β-catenin expression was observed in 54% of ductal carcinomas in situ with highly concordant β-catenin expression patterns in the nearby in situ and invasive components. Conclusions. Quantitative and qualitative changes in β-catenin expression occur in a considerable proportion of in situ and invasive ductal carcinomas and are more prominent in invasive lobular carcinomas.