Human Papillomavirus DNA and p16 Expression in Oral and Oropharyngeal Squamous Cell Carcinoma: A Cross-Sectional...

Human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma is biologically and clinically distinct from conventional tobacco- and alcohol-related head and neck squamous cell carcinoma. Indian data remain heterogeneous because oral cavity and oropharyngeal tumors are often analyzed together despite their different etiologic patterns. This study evaluated p16INK4a (p16) expression and high-risk HPV DNA detection in oral cavity and oropharyngeal squamous cell carcinoma and assessed their association with clinicopathologic variables.

This cross-sectional observational study included 100 adult patients with biopsy-proven squamous cell carcinoma of the oral cavity or oropharynx treated at a tertiary care center in Surat, Gujarat, India. Demographic characteristics, tobacco-related habits, tumor site, clinical presentation, and histopathological findings were recorded. All cases underwent hematoxylin and eosin examination and p16 immunohistochemistry. Fresh tissue was available for high-risk HPV DNA testing in 89 cases and was analyzed for HPV genotypes 16, 18, and 45 using multiplex real-time polymerase chain reaction. Associations were tested using the chi-square test or Fisher's exact test, as appropriate, and effect size was estimated using Cramer's V.

p16 positivity was identified in six of 100 cases (6.0%), and HPV DNA was detected in five of 89 tested cases (5.6%). All p16-positive and HPV DNA-positive patients were male. p16 positivity was significantly more frequent in oropharyngeal tumors than in oral cavity tumors (5/24, 20.8% vs. 1/76, 1.3%; p=0.0028). The base of the tongue was the most common p16-positive subsite (4/6, 66.7%). p16 expression was significantly associated with HPV DNA detection, with five of six p16-positive tumors showing HPV DNA positivity and no HPV DNA detection among p16-negative tumors (Fisher's exact p < 0.001). Most p16-positive cases had no documented history of tobacco chewing, smoking, or alcohol consumption.

p16 expression and HPV DNA detection were uncommon in this Western Indian cohort, likely reflecting the predominance of oral cavity tumors and traditional risk-factor-associated disease. Biomarker-positive cases were concentrated in male patients with oropharyngeal tumors, particularly tumors involving the base of the tongue. Because HPV DNA testing was performed in 89 cases and was limited to genotypes 16, 18, and 45, these findings should be interpreted as a site-aware assessment of common high-risk HPV types rather than a comprehensive estimate of all HPV-driven disease. Combining p16 expression with HPV DNA testing may provide a more balanced assessment of HPV involvement than either test alone, particularly in resource-limited settings.