Significance of transcriptionally-active high-risk human papillomavirus in sinonasal squamous cell carcinoma: Case series and a meta-analysis

Sinonasal cancers represent a highly heterogeneous group of head and neck cancers, for which etiological and prognostic significance of high-risk human papillomavirus (HPV) infections has not yet been conclusively established. We investigated the presence of transcriptionally-active high-risk HPV in a series of 34 sinonasal squamous cell cancer (SNSCC) cases and evaluated the effect of transcriptionally-active HPV on the overall survival. In addition, we performed a meta-analysis of previously published studies, including this study, to summarize the prevalence of HPV positivity across histological subtypes of SNSCC. The presence of transcriptionally-active HPV was detected by HPV mRNA using the polymerase chain reaction (PCR) or in situ hybridization (ISH). p16 expression was evaluated as a surrogate marker for transcriptionally-active HPV infection by immunohistochemistry (IHC), the presence of high-risk HPV DNA was tested by PCR and the HPV genotypes were determined by sequencing of PCR amplicons. Transcriptionally-active HPV infections were found in ~25% of the SNSCC cases. The role of HPV infection in keratinizing SNSCC may be higher than previously reported (~32% in our study vs. ~0-6.3% in all other studies). Patients with transcriptionally-active HPV-positive SNSCCs were more likely to be diagnosed at earlier stages (p<0.05) and displayed better mean overall survival, although the difference between HPV-positive and HPV-negative groups was not statistically significant. In contrast to other non-oropharyngeal squamous cell carcinomas (non-OPSCCs) of the head and neck, in SNSCCs, p16/IHC and p16/IHC+HPV DNA displayed high specificity as surrogate markers of transcriptionally-active HPV infections. However, p16/IHC may have significantly lower sensitivity as a surrogate marker of transcriptionally-active HPV in SNSCCs compared to OPSCCs. Furthermore, in our group of SNSCCs, all cases positive for high-risk HPV DNA by PCR were also transcriptionally-active (causative) infections with positive HPV mRNA by ISH. Our results imply a possible different role of HPV-mediated carcinogenesis of squamous cell epithelium in oropharyngeal and sinonasal sites with the latter displaying a lower proportion of causative HPV infections; nevertheless, most cases positive for high-risk HPV DNA, p16/IHC or combination thereof were also found positive for transcriptionally-active HPV. The prognostic significance of HPV status in SNSCCs remains inconclusive and future studies should investigate the presence of transcriptionally-active HPV by direct HPV testing.