The prognostic significance of hypoxia inducing factor 1-α in oropharyngeal cancer in relation to human papillomavirus status

Objectives: This study examines the prognostic significance of hypoxia inducing factor-1α (HIF-1α) expression in relation to human papillomavirus (HPV) status in oropharyngeal squamous cell carcinoma (SCC). Materials and methods: Clinical details on 233 oropharyngeal SCCs were extracted from institutional databases. Recurrence in any form or death from any cause was recorded for a median of 51 months after diagnosis. HIF-1α expression was evaluated by semiquantitative immunohistochemistry and HPV status was determined by HPV E6-targeted multiplex real-time PCR and p16 immunohistochemistry. Determinants of recurrence and mortality hazards were modeled using Cox regression with censoring at dates of last follow-up. Results: The HIF-1α positivity rate was 58.8%. HIF-1α positivity was associated with higher T category (T3/T4 vs. T1/T2, 64.2% vs. 48.4%, p = 0.001) and lower grade (Grade 1-2 vs. 3, 62% vs. 46.9%, p = 0.001). There was no significant association between HIF-1α expression and HPV status. After adjustment for clinico-pathological variables, HPV status but not HIF-1α was a strong predictor of outcome. The combination of HPV and HIF-1α was not a prognostic variable but the worst outcomes were seen in those with HPV negative and HIF-1α positive cancers. There was no statistically significant evidence of an interaction between HPV and HIF-1α. Conclusions: The degree of hypoxia as measured by HIF-1α expression does not differ between HPV positive and HPV negative cancers. The role of hypoxia in HPV negative oropharyngeal cancer warrants further investigation.