Histologic spectrum and outcome of Human papillomavirus (HPV)-associated oral cavity squamous cell carcinoma: a single center experience and a survey of The Cancer Genome Atlas (TGCA) cohort

While high-risk human papillomavirus (HPV) serves as an essential pathogen and an important prognostic and predictive biomarker for oropharyngeal squamous cell carcinoma, it occurs at low frequency (2.2-6%) in oral cavity squamous cell carcinoma (OCSCC). To date, the pathologic features of HPV-associated OCSCC (HPV( +)-OCSCC) have been sparsely reported and its prognosis is not well-defined. We herein described detailed clinicopathologic features and outcomes of a retrospective series of 27 HPV( +)-OCSCC, including 13 from Memorial Sloan Kettering Cancer Center (MSKCC) and 14 from The Cancer Genomic Atlas program (TCGA). The frequency of HPV positivity in OCSCC was 0.7% in MSKCC cohort and 4.9% in TCGA cohort. Although HPV( +)-OCSCC was predominantly non-keratinizing (in 81%) with various degree of maturation, its histologic spectrum was expanded to include keratinizing subtype (19%), adenosquamous carcinoma (7%), and papillary architecture (subtype, 7%). HPV( +)-OCSCC predominantly affected male patients (male:female ratio = 12.5:1) and (ex) smokers (77%). It might occur in mandibular mucosa, floor of mouth, tongue, retromolar trigone, buccal mucosa, maxillary mucosa, or hard palate. In oral cavity, positivity of HPV by RNA in situ hybridization was required, and p16 immunohistochemistry alone was insufficient to confirm the HPV + status. The positive predictive value of p16 immunopositivity in detecting HPV infection was 68%. HPV-positivity did not appear to affect outcomes, including disease specific survival and progression free survival in OCSCC.