Detection of human papillomavirus infection in oral squamous cell carcinoma: a cohort study of Japanese patients

Objective: Recent evidence suggests that human papillomavirus (HPV)-related head and neck squamous cell carcinoma (HNSCC) is a separate HNSCC subgroup with distinct epidemiology, histopathological characteristics, therapeutic response to chemotherapy and radiation, and clinical outcome. This study aimed to investigate the role of HPV infection in oral squamous cell carcinoma (OSCC) and the correlation between HPV infection, tumor suppressor protein p16 expression, and clinicopathological features in Japanese patients. Methods: In total, 174 OSCC specimens were examined for p16 levels by immunohistochemistry, and p16-positive OSCCs were analyzed for HPV DNA by in situ hybridization (ISH) and HPV genotypes by real-time PCR. The results were evaluated for the association with clinicopathological characteristics of OSCC patients. Results: Twenty-four OSCC samples were found positive for p16 expression; all of them were well-differentiated tumors. P16 immunoreactivity was significantly associated with the invasion depth and tended to correlate with sex, site in the oral cavity, stromal reaction, TNM stage, and survival. HPV DNA was detected in 13 of 24 (54%) p16-positive OSCC by real-time PCR; HPV 16, 18, and other high-risk genotypes were the most prevalent. However, ISH failed to detect HPV DNA in p16-positive OSCCs. Conclusion: P16 immunoreactivity and HPV genotyping by real-time PCR may be useful markers of HPV infection in OSCC. However, although HPV-related OSCC showed good outcomes, HPV infection may have a minor role in oral oncogenesis in Japanese patients.