High levels of expression of cytokeratin 5 are strongly correlated with poor survival in higher grades of mucoepidermoid carcinoma

Aims: Mucoepidermoid carcinoma (MEC) is the most common malignant primary salivary gland tumour. Little is known about cytokeratin expression in MEC or how it may relate to survival. In this study, the aim was to determine the extent of cytokeratin 5 (CK5) expression in intermediate- and high-grade MEC and correlate expression with survival. Methods: Data on clinicopathological features including stage and survival outcome were collected on 29 patients with intermediate- or high-grade MEC that had follow-up for at least 4 years or until death. Staining with antibody to CK5 protein was carried out and tumour staining was stratified as 0-3 (0, no tumour cells staining; 1, 1-25% of tumour cells staining; 2, 26-75% of tumour cells staining; 3, >75% of tumour cells staining). Six patients had intermediate- grade tumours and 23 had high-grade tumours. The median patient follow-up was 33 months, and 11 patients were alive at the end of the study. Results: At the end of the study, 12/13 patients with the highest (>75%) CK5 expression were dead, while 6 of 18 patients with less than 75% expression were dead (p = 0.006, Fisher exact test). When compared with those patients whose tumours had less than 75% expression, patients whose tumours had greater than 75% CK5 expression had much poorer survival times (log-rank test; p <= 0.001). Conclusions: The findings suggest that very high levels of CK5 expression may be a potential marker for worse outcome in intermediate- and high-grade MEC.