Detection and significance of human papillomavirus, CDKN2A(p16) and CDKN1A(p21) expression in squamous cell carcinoma of the larynx

Abstract

While a strong etiologic relationship between human papillomavirus and a majority of oropharyngeal squamous cell carcinomas has been established, the role of human papillomavirus in non-oropharyngeal head and neck carcinomas is much less clear. Here, we investigated the prevalence and clinicopathologic significance of human papillomavirus and its reported biomarkers, CDKN2A(p16) and CDKN1A(p21), in laryngeal squamous cell carcinomas in patients treated either with primary surgery and postoperative radiation or with definitive radiation-based therapy. Nearly all of 76 tumors were keratinizing and none displayed the nonkeratinizing morphology that is typically associated with human papillomavirus infection in the oropharynx. However, CDKN2A(p16) immunohistochemistry was positive in 21 cases (28%), and CDKN1A(p21) in 34 (45%). CDKN2A(p16) and CDKN1A(p21) status strongly correlated with each other (p = 0.0038). Yet, only four cases were human papillomavirus positive by DNA in situ hybridization or by reverse transcriptase polymerase chain reaction E6/E7 mRNA [all four were CDKN2A(p16) and CDKN1A(p21) positive]. Unexpectedly, 9 additional tumors out of 20 CDKN2A(p16) positive cases harbored high-risk human papillomavirus DNA by polymerase chain reaction. For further investigation of this unexpected result, in situ hybridization for E6/E7 mRNA was performed on these 9 cases and all were negative, confirming the absence of transcriptionally active virus. Patients with CDKN1A(p21) positive tumors did have better overall survival (69% at 3 years) than those with CDKN1A(p21) negative tumors (51% at 3 years) [p = 0.045]. There was also a strong trend towards better overall survival in the CDKN2A(p16) positive group (p=0.058). Thus, it appears that the role of human papillomavirus is more complex in the larynx than in the oropharynx and that CDKN2A(p16) and CDKN1A(p21) expression may not reflect human papillomavirus driven tumors in most cases. Because of this, CDKN2A(p16) should not be used as a definitive surrogate marker of human papillomavirus driven tumors in the larynx.

Use of In Situ Hybridization for HPV in Head and Neck Tumors: Experience from a National Reference Laboratory

“…In the same study by Sethi et al [20] it was confirmed that HPV positivity (in large part HPV16), was associated with improved survival and that the survival advantage of HPV-positivity was limited to oropharyngeal sites. Thus, in the absence of evidence for a prognostic role of HPV testing outside of the oropharynx and metastatic neck lymph nodes, these locations may not need HPV-ISH testing unless histologic and/or clinical features otherwise suggest HPV related cancers [21,22]. Utility of low risk HPV testing in head and neck tumors, if any, should also be addressed in future guidelines.…”

Update from the 4th Edition of the World Health Organization Classification of Head and Neck Tumours: What is New in the 2017 WHO Blue Book for Tumours of the Hypopharynx, Larynx, Trachea and Parapharyngeal Space

“…Over the last three decades, the high-risk HPV genotypes (hrHPV) have been confirmed as the major etiologic factor of the subset of oropharyngeal SCC, dominating in the western part of the world [14,15]. The significance of hrHPV infection in the development of tumours in oral cavity, hypopharynx and larynx needs to be additionally elucidated [1,2,[16][17][18]. Controversial data on hrHPV DNA prevalence in hypopharyngeal and laryngeal SCC has been published; prevalence varied considerably, from 5 to 60% [4,19,20].…”

“…Thus only integrated and transcriptionally active forms of hrHPV contribute in HPV-related carcinogenesis. HPV E6 and E7 oncoproteins are now established as standard biomarkers for oncogenic activity of hrHPVs, together with more than 70% positivity of p16 protein in tumour cells [4,18,19,23,24]. HPVrelated laryngeal and hypopharyngeal SCC is histologically mostly non-keratinizing SCC, but focally may be also keratinizing.…”

Approach to Metastatic Carcinoma of Unknown Primary in the Head and Neck: Squamous Cell Carcinoma and Beyond

“…It is also easy to perform and interpret. However, outside of the oropharynx, p16 overexpression loses specificity for transcriptionally-active HPV among head and neck SCCs [21]. In addition, approximately 20 % of aggressive cutaneous head and neck SCCs may show diffuse p16 positivity that is unrelated to high-risk HPV, including in their lymph node metastases [22].…”