β-Catenin Expression in Oropharyngeal Squamous Cell Carcinomas: Comparison and Correlation with p16 and Human Papillomavirus in situ Hybridization

Abstract

Background: The Wnt/β-catenin signaling pathway has been noted to be upregulated in head and neck cancers, including oropharyngeal squamous cell carcinoma (OSCC). This study compared the efficacy of β-catenin immunohistochemistry (IHC), p16 IHC and automated human papillomavirus (HPV) in situ hybridization (ISH) in OSCC. Methods: Sixty-eight OSCCs (48 surgical specimens and 20 fine-needle aspirations) were evaluated. Nuclear staining only of β-catenin was assessed as 0-3+ intensity (relative to controls of benign squamous mucosa). p16 was interpreted as positive if 70% of tumor cells showed brown nuclear and cytoplasmic staining. HPV ISH was interpreted as positive if a minimum of one tumor cell showed brown punctate dot-like nuclear positivity. p16 IHC and HPV ISH were then correlated with β-catenin staining. HPV ISH was used as the gold standard. Results: Twenty-five of 48 surgical specimens (52.1%) and 11 of 20 cell blocks (55%) stained positively for β-catenin, making a total of 36 of 68 (52.9%) staining positively for β-catenin, as compared to 61.7% positive for p16 IHC and 70.6% positive by automated HPV ISH, the gold standard method for OSCC diagnosis. χ² analysis revealed no significant correlation between β-catenin and HPV ISH (p > 0.05) and demonstrated a strong correlation between p16 and HPV ISH (p < 0.05). Conclusion: β-Catenin IHC is not a sensitive or specific marker of HPV and is unlikely to be a useful adjunct to p16 IHC or HPV ISH in the setting of advanced OSCC. However, as this study focused on samples of advanced OSCC, β-catenin IHC may still find some use in the diagnosis of early-stage OSCC.