Increased Expression Of p16 In Oral Leukoplakia The Last Decade

Objectives: During the last two decades an increase in incidence of oropharyngeal carcinomas related to Human Papilloma Virus (HPV) infection has been reported. Although a casual association between lekoplakia (LPL), oral cancer and HPV has been suggested in several reports, no conclusive evidence has been presented. To assess presence of HPV, the tumour suppressing protein p16 is commonly used as a surrogate marker for HPV infection.
The aim of the present study is to investigate whether p16 expression in tissue specimens from LPL has increased during the last decade, which may indicate an increase in incidence of oral HPV infection.
Methods: A patient cohort with tissue specimens obtained between 1992-2001 (N=98) and a cohort (N=73) where specimens were obtained between 2011-2015 and with histopathological diagnoses of benign hyperkeratosis or hyperkeratosis with dysplasia were examined. Immunohistochemistry was performed using a monoclonal antibody (clone E6H4; Roche Ltd) visualizing p16. Digitalized images of sections were obtained and a semiquantitative scale (0-5) was used to enumarate p16 expression in oral epithelium.
Statistical analysis: Fischer s exact test.
Results: In the 2011-2015 cohort LPL epithelium showed a significant increase (P=0.02) in grade 4 and 5 p16 expression in comparison with LPL epithelium in the 1992-2001 cohort. In LPL presenting with dysplasia, grade 4 and 5 p16 expression also increased significantly (P=0.0001) over time when comparing the cohorts.
Conclusions: The results indicate an increase in HPV infection in LPL during the last decade. Further investigation of presence of HPV DNA utlizing PCR is presently undertaken