The ability of the eighth edition of the TNM staging system plus minor invasion criteria to predict the biological behaviour of oral cavity carcinomas

Background: Oral squamous cell carcinoma (OSCC) treatment is based largely on the TNM stage. The eighth edition includes important new prognostic parameters (extranodal extension and depth of invasion), while it does not consider tumour molecular characteristics or minor invasion criteria (perineural and lymphovascular invasion, grading and resection margins). This study evaluated how well the TNM eighth edition predicts the biological behaviour of OSCC, considering survival and risk of locoregional recurrence. Materials and methods: Data from 217 patients treated for OSCC were analysed, including epidemiologic characteristics, histological features and treatment. Results: No significant correlations with overall survival or tumour recurrence were found for pT stages and the type of treatment, while different pN stages had significant differences in recurrence, but not in overall survival. We found significant correlations between overall survival and tumour grade and lymphovascular and perineural invasion and a significant correlation between tumour resection margins and the risk of recurrence. Conclusions: The current TNM staging system is a necessary but not sufficient tool for predicting the overall survival and risk of recurrence of OSCC. It could be improved by considering other factors, such as minor invasion criteria and biological markers.