Population-based evidence of increased survival in human papillomavirus-related head and neck cancer

Abstract

Background: Evidence from clinical, population-based and molecular studies has shown that human papillomavirus (HPV) infection can be a causal risk factor for a subset of head and neck squamous cell carcinomas (HNSCC). It is proposed that HPV-associated oropharyngeal cancer is a new disease entity that requires treatment and prevention strategies distinct from present recommendations.

Methods: In our population-based study we estimated incidence and survival trends in 8270 patients with HPV-related HNSCC (HPV(+)HNSCC) and HPV-unrelated HNSCC (HPV(-)HNSCC) in Norway over the past three decades.

Results: In the period 1981-1995, patients with HPV(+)HNSCC had poorer survival than HPV(-)HNSCC (adjusted hazard ratio (HR) 1.3, 95% confidence interval (CI): 1.14-1.44). By 1996-2007, survival had increased in both groups, but the increase was significantly greater among HPV(+)HNSCC patients (HR 0.57, 95% CI: 0.48-0.67). During the same period, incidence also increased, but only for HPV(+)HNSCCs. From 1981-1995 to 1996-2007, median age at diagnosis for HPV(+)HNSCC decreased from 63.2 to 59.8 years, while for HPV(-)HNSCC median age at diagnosis of 66.6 years remained unchanged.

Conclusions: We demonstrate a population level improvement in survival among patients with oropharyngeal squamous cell cancers commonly related to infection with HPV. In contrast, patients with HNSCC not related to HPV only showed a modest improvement in survival in the period 1981-2007. A concomitant increase in incidence and survival was observed for HPV-related cancers only. This trend cannot be explained by changes in treatment, cancer registration nor screening, but is most likely due to an increased prevalence of HPV-positive tumours.