TP53 protein overexpression in oral squamous cell carcinomas (OSCC): Correlation with histologic variables and survival outcome in Pakistani patients

Aim: TP53 gene mutation and overexpression of its protein is widely recognised as the commonest event in the most malignancies including development of oral cancer. Alteration of TP53 in oral squamous cell carcinoma (OSCC) is believed to be associated with reduced overall survival (OS) and disease-free survival (DFS). The purpose of this study is to determine whether TP53 protein overexpression in OSCC is prognostic indicator of patient survival along with its correlation with smoking, chewing habits, histological variables like grade & stage of the tumour in a high risk population. Material and methods: A total of 140 patients of OSCC were included in this study. TP53 protein overexpression was investigated by means of immunohistochemistry. Clinical and histopathological data was gathered, and correlation with survival and histologic variable was analysed. Results: Overexpression of TP53 protein was observed in 75 patients (54%) using a threshold of 10% stained cell nuclei. In univariate Cox regression analysis, TP53 overexpression was significantly associated with shortened OS (HR = 1.8; P = 0.033). However, Multivariate Cox regression analysis did not reveal independent association of TP53 overexpression with reduced OS and DFS. Multivariate analysis revealed that histological grade (P = 0.046), T (P = 0.045), and N stage (P < 0.001) were significantly independent prognostic variables. Conclusion: Overexpression of TP53 protein was not an independent prognosticator of tumour behaviour in patient with OSCC. However, histological grade and N stage are two common, independent risk factors for reduced overall and DFS.