HPV-Associated p16 INK4A Expression and Response to Therapy and Survival in Selected Head and Neck Cancers

Background: Development of squamous cell cancer of head and neck (SCCHN) is associated with human papillomavirus (HPV) infection, which in turn is closely related with expression of $p16^{INK4A}$. Loss of $p16^{INK4A}$ expression by deletion, mutation, or hypermethylation is common in SCCHN. We here evaluated $p16^{INK4A}$ as a prognostic marker of treatment response and survival in our SCCHN patients with laryngeal, hypopharyngeal or nasopharyngeal cancers. Materials and Methods: 131 patients diagnosed with SCCHN between January 2,2006 and July 17, 2010 were examined for $p16^{INK4A}$. The median age was 60 years (15-82 years). Fifty one patients were stage I-II and 80 were stage III-IV. Immunohistochemical expression of $p16^{INK4A}$ was analyzed in pretreatment paraffin-embedded tumor blocks. The influence of $p16^{INK4A}$ status on disease-free survival, and overall survival after treatment was evaluated. Results: $p16^{INK4A}$ positivity was found in 58 patients (44%). Tumor-positivity for$ p16^{INK4A}$ was correlated with improved disease free survival (70.1 months vs 59 months) and improved overall survival (2, 3 and 5-year values; 77% vs 72%, 70% vs 63% and, 63% vs 55%; respectively). On multivariate analysis, stage was determined as independent prognostic factor for disease-free survival. Conclusions: Stage was the major prognostic factor on treatment response and survival in our patients. $p16^{INK4A}$ status predicts better outcome in laryngeal, hypopharyngeal or nasopharyngeal cancer cases treated with surgery plus adjuvant radiochemotherapy as well as with definitive radiation therapy and/or chemotherapy.