Prognostic relevance of epithelial-mesenchymal transition and proliferation in surgically treated primary parotid gland cancer.

Aims: Cancer of the major salivary glands comprises a morphologically diverse group of rare tumours of largely unknown cause. Epithelial-mesenchymal transition (EMT) has been shown to play a significant prognostic role in various human cancers. The aim was to assess the expression of EMT markers in different histological subtypes of parotid gland cancer (PGC) and analyse their prognostic value.

Methods: We examined 94 PGC samples (13 histological subtypes) for the expression of MIB-1, epithelial cadherin (E-cadherin), β-catenin, vimentin and cytokeratin 8/18 (CK8/18) by means of immunohistochemistry. The experimental findings were correlated with clinicopathological and survival parameters.

Results: We detected all analysed EMT and proliferation markers in specifically different constellations within the examined histological subtypes of PGC. We found high epithelial marker expressions (CK8/18, E-cadherin, membranous β-catenin) only in a distinct variety of carcinomas. A high proliferation rate (high MIB-1 expression) as well as a combination of high CK8/18 and low vimentin expression was associated with a significantly worse survival.

Conclusions: Our findings indicate that activation of the EMT pathway is a relevant explanation for tumour progression in individual histological subtypes of malignant parotid gland lesions, but by far not in all. Evidence of EMT activation in PGC cannot be seen as an isolated prognostic factor.