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 p16INK4A 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.