Oropharyngeal Squamous Cell Carcinoma Outcomes by p16^INK4a Antigen Status in a Veteran Population

The correlation between head and neck squamous cell carcinoma (SCC) and human papillomavirus (HPV) has been of great interest. We aimed to study immunoexpression of the p16^INK4a (p16) antigen, a surrogate marker for high-risk HPV infection, in oropharyngeal SCC among veterans to estimate HPV-related cancer and survival. Secondary aims included stratification of race and ethnicity, degree of tobacco and alcohol use, tumor location, stage, and age at diagnosis.

A retrospective electronic health record review was performed between January 1, 2000, and December 31, 2008, at a tertiary-level US Department of Veterans Affairs (VA) medical center for veterans who were treated for oropharyngeal SCC, had follow-up for a minimum of 2 years, and for whom paraffin-embedded tissue was available. Paraffin-embedded tissue was analyzed for p16 expression.

We identified 66 veterans who met the inclusion criteria. p16 expression was observed in 29% of the patients. All patients were male with no difference in age at diagnosis between the groups. Among patients with p16-negative status, 60% were African American, whereas among patients with p16-postive status, 32% were African American (P = .04). Among patients with p16-postive status, 22% were tobacco-naïve, and 18% were alcohol-naïve vs 0% and 4%, respectively, of patients with p16-negative status (P = .005 and P = .12, respectively). Two-year survival was the same for both groups (P = .52).

We observed p16 expression in 29% of VA patients with oropharnygeal SCC, which was less than observed in non-VA populations. At presentation, both groups demonstrated a predilection for tonsil location and late stage without significant difference in age or disease-specific survival. Disparities in racial distribution and tobacco use between patients with and without p16-positive status appear like that reported in non-VA populations; however, the frequently reported younger age at presentation, lower stage, and improved prognosis were not observed.