In situ hybridization for high-risk HPV E6/E7 mRNA is a superior method for detecting transcriptionally active HPV in oropharyngeal cancer

Abstract

Current human papillomavirus (HPV) detection methods in oropharyngeal squamous cell carcinoma (OPSCC) have varying sensitivity and specificity. We aimed to compare different HPV-detection methods against the test used in clinical practice, ie, p16 immunohistochemistry (IHC) and to evaluate whether another HPV-detection test additional to p16 IHC would be worthwhile in OPSCC specimens. The study cohort comprised 357 consecutive OPSCC patients during two time periods: 2000-2009 and 2012-2016. From tumor tissue slides, HPV mRNA via in situ hybridization (ISH), HPV DNA via ISH and HPV DNA via polymerase chain reaction (PCR) were detected. The results of these methods were compared with p16 IHC results. Additionally, clinicopathological factors were compared with the methods studied. The sensitivity of HPV mRNA ISH, HPV DNA ISH and HPV DNA PCR were 93.4%, 86.3%, and 83.5%, respectively. The corresponding specificity was 92.4%, 95.3%, and 89.1%, respectively. The negative predictive value for p16 IHC was highest (89.0%) when using mRNA ISH, and followed by DNA ISH (83.5%). ISH for high-risk HPV E6/E7 mRNA was found to be a highly specific and sensitive method for detecting HPV in OPSCC. As p16 protein may be overexpressed due to HPV-independent mechanisms, all p16 IHC-positive OPSCCs should be considered for retesting using mRNA ISH in order to verify transcriptionally active HPV. This is especially critical when considering de-escalated treatment approaches for patients with HPV-positive tumors and still maintaining favorable outcomes for this subgroup of patients.