P16^INK4a Correlates to Human Papillomavirus Presence, Response to Radiotherapy and Clinical Outcome in Tonsillar Carcinoma

Abstract

Background: Human papillomavirus (HPV) in tonsillar carcinoma is correlated with favourable clinical outcome. Here, p16^INK4A, in situ HPV DNA hybridisation (ISH) and HPV L1 capsid detection were evaluated in tonsillar carcinoma to predict the response to radiotherapy (RT) and prognosis. Materials and Methods: Fifty-one pre-treatment paraffin-embedded tonsillar cancer biopsies were analysed. Immunohistochemistry (IHC) was used for p16^INK4A and HPV L1 capsid analysis and PCR and ISH for HPV detection. Results: High-risk HPV DNA was detected by PCR in 49% of the tumours. P16^INK4a staining was correlated to HPV. In the high-grade p16^INK4a staining group, 94% had a complete RT response. High p16^INK4a staining as well as the HPV PCR-positive cases had a favourable prognosis. HPV DNA ISH and L1 IHC could not predict RT response or clinical outcome. Conclusion: P16^INK4a overexpression was correlated to HPV in tonsillar carcinoma and is useful for predicting RT response and prognosis in tonsillar carcinoma patients.