Prevalence of p16-positive Squamous Cell Carcinoma of the Oropharynx in a Tertiary Government Hospital in the Philippines

Abstract

Objective. This study aimed to determine the hospital-based prevalence of human papilloma virus (HPV)-associated oropharyngeal squamous cell carcinoma (SCC) among patients in a tertiary government institution in the Philippines using immunohistochemical (IHC) staining for p16 as surrogate marker. 

Methods. This retrospective cross-sectional study included patients with oropharyngeal SCC from January 1, 2015 to December 31, 2021 who had available histopathology tissue blocks. Age, sex, and primary tumor site were extrapolated from charts and p16 status was determined using immunohistochemistry staining. Chi-square test and Fisher’s exact tests were performed for select variables and p16 positivity. A p-value of <0.05 was deemed significant. 

Results. Seventy-six patients were included, aged 32 to 84 years (mean: 61 years). Most were men (n=60, 78.9%), with male to female ratio of 3.75:1. The mean age of patients who were p16-positive were 5 years younger than p16-negative patients, although this was not found to be statistically significant (p=0.03, with Bonferroni Correction). Overall institutional p16-positive oropharyngeal SCC prevalence was 47.4% (n=36). More men (n=32, 88.9%) had p16-positive tumors compared to women (n=4, 11.1%), although sex only had a tendency for association with p16 status (p=0.053). There was no significant difference between p16 positivity across age groups. Majority with p16-positive results had tumors that were located in the tonsils (n=19, 52.8%). However, tumor subsite was not found to have statistically significant association with p16 status.

Conclusion. The prevalence of HPV-associated oropharyngeal SCC was 47.37%, which was comparable to neighboring Asian countries – Japan and Taiwan. Multicenter studies with larger sample sizes may be explored for future investigations.