Functionally impactful TP53 mutations are associated with increased risk of extranodal extension in clinically advanced oral squamous cell carcinoma

Background: The treatment of advanced oral squamous cell carcinoma (OSCC) is a clinical challenge because it is unclear which therapeutic approaches are the best for this highly heterogeneous group of patients. Because TP53 mutations are the most common genetic event in these tumors, the authors investigated whether they could represent an ancillary biomarker in the management of advanced OSCC. Methods: The TP53 gene was sequenced in 78 samples from patients with advanced OSCC who received treatment at 2 institutions located in the United States and Brazil. TP53 mutations were classified according to an in-silico impact score (the evolutionary action score of p53 [EAp53]), which identifies mutations that have greater alterations of p53 protein function (high-risk). Associations between TP53 mutation status/characteristics and clinicopathologic characteristics were investigated. The relevant findings were validated in silico by analyzing 197 samples from patients with advanced OSCC from The Cancer Genome Atlas. Results: No differences in clinical outcomes were detected between patients with TP53-mutant and wild-type TP53 disease. However, patients who had tumors carrying high-risk TP53 mutations had a significantly increased risk of developing extranodal extension (ENE) compared with those who had wild-type TP53-bearing tumors. The increased chances of detecting ENE among patients who had high-risk TP53 mutations was validated among patients with advanced OSCC from The Cancer Genome Atlas cohort. Conclusions: High-risk TP53 mutations are associated with an increased chance of detecting ENE in patients with advanced OSCC. Because ENE is 1 of the major factors considered for OSCC patient management, TP53 mutation status may represent a potential ancillary biomarker for treatment decisions regarding postoperative adjuvant therapy.