Differences in p63 expression in SCCHN tumours of different sub-sites within the oral cavity.

Squamous cell carcinoma of the head and neck, SCCHN, the sixth most common cancer in the world, comprises tumours of different anatomical sites. The overall survival is low, and there are no good prognostic or predictive markers available. The p53 homologue, p63, plays an important role in development of epithelial structures and has also been suggested to be involved in development of SCCHN. However, most studies on p63 in SCCHN have not taken into account the fact that this group of tumours is heterogeneous in terms of the particular site of origin of the cancer. Mapping and comparing p63 expression levels in tumours and corresponding clinically normal tissue in SCCHN from gingiva, tongue and tongue/floor of the mouth revealed clear differences between these regions. In normal samples from tongue and gingiva, tongue samples showed 2.5-fold higher median p63 expression and also more widespread expression compared to gingival samples. These results emphasise the importance of taking sub-site within the oral cavity into consideration in analyses of SCCHN.