Impact of p16 expression, nodal status, and smoking on oncologic outcomes of patients with head and neck unknown primary squamous cell carcinoma.

BACKGROUND The prognostic significance of human papillomavirus (HPV) in the context of head and neck squamous cell carcinoma (HNSCC) of cancer of unknown primary (CUP) origin is unclear. METHODS Patients treated for CUP at the Princess Margaret Cancer Centre between 2001 and 2013 were stratified by p16 status and retrospectively reviewed. RESULTS Of the 73 patients included, those with p16-positive tumors (63%) had less advanced nodal status (N1-N2b; 52% vs 89%; p = .035) and less aggressive treatment. Patients with p16-positive tumors had improved 3-year disease-free survival (DFS; 79% vs 56%; p = .012) independent of nodal status and treatment in multivariable analysis (hazard ratio [HR] = 0.27; 95% confidence interval [CI] = 0.08-0.95). CONCLUSION Among patients with CUP, p16-positive status is an independent predictor of DFS but not overall survival (OS). © 2016 Wiley Periodicals, Inc. Head Neck, 2016 © 2016 Wiley Periodicals, Inc. Head Neck 38: 1347-1353, 2016.