Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Master of Science

Program

Pathology and Laboratory Medicine

Supervisor

McCord, Christina

2nd Supervisor

Khan, Zia

Co-Supervisor

3rd Supervisor

Lapointe, Henry

Co-Supervisor

Abstract

The role of high-risk human papillomavirus (HR-HPV) is well documented in oropharyngeal squamous cell carcinoma and cervical cancer. Although a subset of oral dysplastic lesions have been associated to HPV infection as well, there is currently limited data characterizing these lesions. We identified HPV-associated oral epithelial dysplasia (HPV-OED) through screening for histopathological features of HPV and p16INK4a immunoreactivity. Transcriptionally active infections were confirmed by performing RT-qPCR to identify E6 mRNA expression. We identified 82 cases of confirmed HPV-OED that showed a strong predilection for male patients and anatomical sites such as floor of mouth and ventral tongue. This group had a median age of 56.1 years. The utility of E6 immunohistochemistry was tested as a diagnostic marker and was deemed inconclusive. Interestingly, there was significant recurrence of lesions in our population (18%) and infrequent progression to malignancy (<1%).

Summary for Lay Audience

Human papillomaviruses are viruses that infect the skin of various areas on the human body, including the mouth, throat, and genital tracts. Their role in the initiation and progression of throat and genital cancer has been well established. Recently, there have been reports of similar HPV infections causing precancerous disease in the oral cavity named HPV-associated oral epithelial dysplasia. These lesions can be identified through screening for certain microscopic features and specific immunological staining. To this date, there is limited scientific data showing the characteristics of these lesions and long-term behavior when compared to precancerous lesions that are not associated to HPV infection. Our research identified 82 cases of confirmed HPV infection and showing precancerous cellular changes. The cases tend to occur more frequently in male patients and affect the tongue/floor of mouth. A significant finding was that these type of lesions did not seem to progress to cancer in most cases while also showing a tendency to recur. Future studies from this large sample of cases will attempt to characterize these lesions further with a longer follow up period and a potential for further molecular investigations.

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