Supplementary Material for: <b><i>TP53</i></b> Y220C Is a Hotspot Mutation in Oropharyngeal Squamous Cell Carcinoma

<b><i>Objectives:</i></b> Although <i>TP53</i> mutations in head and neck squamous cell carcinoma (HNSCC) have been extensively studied, their association with the different subsites in the head and neck region has never been described. <b><i>Methods:</i></b> Sanger sequence analysis evaluating exons 4-9 in the <i>TP53 </i>gene was performed on 116 HNSCC patients. The exon location, exact codon and corresponding substitution in relation to the anatomical site (subsite) of the HNSCC were evaluated. <b><i>Results:</i></b> We found nonsynonymous <i>TP53</i> mutations in 70% (81/116) of the patients. In oral cavity carcinomas, most mutations occurred in exon 7 (37%). In oropharyngeal and laryngeal tumors, mutations were mainly found in exons 6 and 7. The most common mutation was located in codon 220, and all of these were an Y220C mutation. Five out of nine (56%) Y220C mutations occurred in oropharyngeal tumors. Additionally, 22% of all mutations observed in oropharyngeal squamous cell carcinoma (OPSCC) consisted of Y220C mutations. <b><i>Conclusion:</i></b> In this study, the subsite-related distribution of <i>TP53</i> mutations underlines the biological diversity between tumors arising from different anatomical regions in the head and neck region. Moreover, the Y220C mutation was by far the most prevalent <i>TP53</i> mutation in HNSCC and a relative hotspot mutation in the oropharynx.