A proposal for classification of oropharyngeal squamous cell carcinoma: Morphology and status of HPV by immunohistochemistry and molecular biology

Abstract

The current three‐tier grading system (well, moderate and poorly differentiated) used to morphologically classify head and neck squamous cell carcinoma (HNSCC) is inadequate for categorisation of oropharyngeal squamous cell carcinoma (OPSCC) owing to the lack of prognostic value. The aim of this study was to assess the validity of a classification system for OPSCC based on morphology and human papilloma virus (HPV) infection status. Haematoxylin and eosin slides of 121 patients (100 M, 21 F, age range 40‐89 years) with OPSCC were reviewed and categorised as histological types I, II and III. The presence of HPV was assessed by immunohistochemistry with p16 and RNAscope In situ hybridization (ISH). The follow‐up period was 36 months. Ninety‐six patients were p16+ and clinical stage I. Patient survival with types I, II and III was 93%, 50% and 96%, respectively. Twenty‐five patients were p16−: 10 clinical stage I and 15 stage III. Amongst this group, no type I morphology was identified. At follow‐up, 65% of type II and 75% of type III patients were alive. All p16+ cases were also positive for E6/E7 mRNA high‐risk HPV by ISH, while 23 p16− cases were negative and two were positive. Cox regression identified three predictors of mortality: older age (HR = 1.14, 95% CI = 1.06‐1.23, P = .001); female gender (HR = 0.22.95% CI 0.05‐0.88, P = .033); and type II morphology (HR = 13.1, 95% CI = 1.09‐157.0, P = .043). OPSCC morphological classification in three sub‐types, along with HPV infection status, seems to reflect the outcome of patients with OPSCC.

RNA in situ hybridization for human papillomavirus testing in oropharyngeal squamous cell carcinoma on a routine clinical diagnostic platform

“…Reference to negative controls is necessary to distinguish low HPV transcript signals from non-specific punctate staining. [26][27][28] We show that such control tissue must be stained on the same slide as the test tissue, since in this study we observed heterogeneity in…”

“…In keeping with the observation by Rooper et al, 19 all discordant cases in our study were restricted to cases with low signal intensity and/or transcript number indicating the necessity for observer training and calibration in RNA ISH interpretation. Reference to negative controls is necessary to distinguish low HPV transcript signals from non‐specific punctate staining 26‐28 . We show that such control tissue must be stained on the same slide as the test tissue, since in this study we observed heterogeneity in staining patterns of serial sections placed on different slides during the same test run.…”

Positive Linear Relationship between Nucleophosmin Protein Expression and the Viral Load in HPV-Associated Oropharyngeal Squamous Cell Carcinoma: A Possible Tool for Stratification of Patients

“…All cases show non-keratinized (“basaloid”) and mixed-type (“keratinized” and “basaloid”) SCC morphology [ 32 ] and positive p16 immunohistochemical staining according to the Lewis et al, criteria ( Figure 1 b) [ 33 ].…”

HPV Detection in Head and Neck Squamous Cell Carcinomas: What Is the Issue?

“…Studies about RNA ISH have been rising in the last 10 years and showing excellent diagnostic performances. Sensitivities vary from 87 to 100%, and specificities vary from 88 to 100%, being more frequently around 95% ( 62 – 65 , 69 – 72 ). Importantly, studies using RT-PCR as the reference test found the best diagnostic performances, making RNA ISH the method of choice for detecting high-risk HPV infections ( 62 , 65 , 71 ).…”