Human papillomavirus in oropharyngeal squamous cell carcinoma in South-Eastern Norway: prevalence, genotype, and survival.

The objectives of this study were to assess the prevalence of high-risk human papillomavirus (HR HPV) and survival in all oropharyngeal cancer (OPSCC) patients in a Norwegian population cohort in 2010-2011. Clinical data were retrieved from hospital records. Biopsies from 166 patients were tested for the presence of HR HPV by qualitative polymerase chain reaction (qPCR). p16 immunohistochemistry was performed in 138 cases. Survival was compared between groups of patients with tumors positive for HPV16 and other HR HPV genotypes, and patients with HPV negative tumors. HR HPV was detected in 127 out of 166 cases (77%). HPV16 was the most prevalent genotype (n = 108), followed by HPV33 (n = 12), HPV18 (n = 3), and HPV31/35/56/59 (n = 1). There was a robust and significant association between p16 and HR HPV status. (Chi square 70.8; p < 0.0001). Among p16-positive/HR HPV-positive cases, the distribution of HPV16 and other HR HPV types was not significantly different [91% (88/97) versus 82% (14/17); p = 0.30]. HR HPV-negative patients had reduced overall survival compared to HR HPV-positive patients [hazard ratio 0.30; 95% confidence interval (CI) 0.16-0.56, p < 0.001]. Non-HPV16 HR HPV-positive patients had significantly poorer overall survival than HPV16-positive patients (hazard ratio 0.35; 95% CI 0.14-0.85, p = 0.02). Prevalence of HR HPV in OPSCC in Norway is high, and similar to the level reported in recent years from other countries in Northern Europe and in North America. HPV genotyping may be valuable in future risk-stratification algorithms for treatment of patients with HPV-positive OPSCC.