Immunohistochemical Evaluation of p16 and p53 in Oral and Oropharyngeal Squamous Cell Carcinoma with Special Regard to Human Papillomavirus Status.

Background: Incidence of human papillomavirus (HPV)-associated oral and oropharyngeal squamous cell carcinomas (OSCC and OPSCC) is on a rising trend globally and has specific therapeutic implications. HPV-related tumors have a distinct pathogenetic mechanism targeting p16 and p53 both. However, there are limited studies evaluating p16 and p53 expression in combination. Aim: The aim of the study is to evaluate p16 and p53 immunohistochemical expression pattern in OSCC and OPSCC, with special reference to HPV association. Study Design: This was a hospital-based prospective study done over 22 months (September 2018 to June 2020), including a total of 54 cases of OSCC and OPSCC. They were subjected to clinicopathological evaluation, p16 and p53 immunohistochemistry, and DNA polymerase chain reaction testing for testing of HPV association, followed by analysis of data by statistical methods. Results: Out of 54, 43 cases were OSCC and 11 cases were OPSCC. A total of nine cases were HPV positive. HPV association was found to be significant with tonsil as primary site, age range between 40 and 60 years, and absence of tobacco or alcohol habit. Presence of HPV infection was also significantly associated with p16 overexpression, in combination with p53 negativity. The findings indicate that p16 overexpression combined with a negative p53 expression can be used for HPV detection and the former alone may be used as diagnostic marker in OPSCC only. Conclusion: HPV-associated OSCC and OPSCC are a unique subset of cancers, and using combination of molecular biomarkers could help in diagnosis and prognosis.